MPMS MultiVu Application UserÕs Manual - Our Story · PDF fileQuantum Design MPMS MultiVu Application UserÕs Manual i CONTENTS Table of Contents PREFACE Contents and Conventions

Magnetic Property Measurement System

MPMS MultiVu Application User’s Manual

Part Number 1014-110C

Quantum Design 6325 Lusk Blvd. San Diego, CA 92121 USA Technical support (858) 481-4400 (800) 289-6996 Fax (858) 481-7410 Third edition of manual completed November 2004.

Trademarks All product and company names appearing in this manual are trademarks or registered trademarks of their respective holders.

U.S. Patents 4,791,788 Method for Obtaining Improved Temperature Regulation When Using Liquid Helium Cooling 4,848,093 Apparatus and Method for Regulating Temperature in a Cryogenic Test Chamber 5,053,834 High Symmetry DC Squid System 5,110, 034 Superconducting Bonds for Thin Film Devices 5,139,192 Superconducting Bonds for Thin Film Devices 5,311,125 Magnetic Property Characterization System Employing a Single Sensing Coil Arrangement to Measure AC

Susceptibility and DC Moment of a Sample (patent licensed from Lakeshore) 5,319,307 Geometrically and Electrically Balanced DC Squid System Having a Pair of Intersecting Slits 5,647,228 Apparatus and Method for Regulating Temperature in Cryogenic Test Chamber

Foreign Patents U.K. 9713380.5 Apparatus and Method for Regulating Temperature in Cryogenic Test Chamber Canada 2,089,181 High Symmetry DC Squid System Japan 2,533,428 High Symmetry DC Squid System Japan 2,533,428 High Symmetry DC Squid System

Quantum Design MPMS MultiVu Application User’s Manual i

C O N T E N T S

Table of Contents PREFACE Contents and Conventions ..............................................................................................................................xiii

P.1 Introduction ......................................................................................................................................................xiii P.2 Scope of the Manual.........................................................................................................................................xiii P.3 Contents of the Manual ....................................................................................................................................xiii P.4 Conventions in the Manual...............................................................................................................................xiv

CHAPTER 1 Introduction to MPMS MultiVu ................................................................................................................. 1-1

1.1 Introduction ..................................................................................................................................................... 1-1 1.2 Overview of the MPMS MultiVu Application ................................................................................................ 1-1

1.2.1 Immediate Mode and Sequence Mode Operation..................................................................................... 1-1 1.2.2 Data Viewing............................................................................................................................................ 1-2 1.2.3 Comparison with the MPMSR2 DOS Software ....................................................................................... 1-2

1.3 Starting Up MPMS MultiVu ........................................................................................................................... 1-3 CHAPTER 2 MPMS MultiVu Interface .............................................................................................................................. 2-1

2.1 Introduction ..................................................................................................................................................... 2-1 2.2 Function of the MPMS MultiVu Interface ...................................................................................................... 2-1

2.2.1 MDI Application Interface ....................................................................................................................... 2-1 2.3 Features of the MPMS MultiVu Interface ....................................................................................................... 2-2

2.3.1 Menu Bar .................................................................................................................................................. 2-3 2.3.2 Pop-up Menus........................................................................................................................................... 2-3 2.3.3 Tool Bar.................................................................................................................................................... 2-4 2.3.4 Control Center .......................................................................................................................................... 2-6 2.3.5 Status Bar.................................................................................................................................................. 2-7

2.3.5.1 Sequence Status Panels...................................................................................................................... 2-7 2.3.5.2 Field Status Panels............................................................................................................................. 2-8 2.3.5.3 Temperature Status Panels................................................................................................................. 2-8 2.3.5.4 Chamber Status Panels ...................................................................................................................... 2-9

2.3.6 Data File Windows ................................................................................................................................... 2-9 2.3.7 Sequence Windows .................................................................................................................................. 2-9

Contents Table of Contents

ii MPMS MultiVu Application User’s Manual Quantum Design

CHAPTER 3 Sample Measurement....................................................................................................................................... 3-1

3.1 Introduction ..................................................................................................................................................... 3-1 3.2 Overview of Sample Measurements................................................................................................................ 3-1 3.3 Measuring the Sample ..................................................................................................................................... 3-2

3.3.1 Attach the Sample..................................................................................................................................... 3-2 3.3.2 Insert the Sample ...................................................................................................................................... 3-3 3.3.3 Define the Sample Parameters.................................................................................................................. 3-5 3.3.4 Center the Sample..................................................................................................................................... 3-6

3.3.4.1 Initialize the Sample Transport.......................................................................................................... 3-7 3.3.4.2 Define the Parameters........................................................................................................................ 3-8 3.3.4.3 Run the Centering Measurement ....................................................................................................... 3-9 3.3.4.4 Adjust the Sample Position.............................................................................................................. 3-11

3.3.5 Measure the Sample................................................................................................................................ 3-12 3.3.5.1 Define the Parameters...................................................................................................................... 3-12 3.3.5.2 Select the Data Files ........................................................................................................................ 3-13 3.3.5.3 Run the Measurement ...................................................................................................................... 3-14 3.3.5.4 View the Data Files ......................................................................................................................... 3-14

3.4 Measurement Algorithms .............................................................................................................................. 3-15 3.4.1 Iterative Regression Algorithm............................................................................................................... 3-15 3.4.2 Linear Regression Algorithm ................................................................................................................. 3-16 3.4.3 Full Scan Algorithm ............................................................................................................................... 3-16

3.5 Measurement Considerations ........................................................................................................................ 3-17 3.6 Multiple Measure Sequence Command......................................................................................................... 3-17

3.6.1 Compatibility .......................................................................................................................................... 3-17 3.6.2 Accessing and Using Multiple-Measure Command ............................................................................... 3-18 3.6.3 Checking the Status of a Multiple-Measure Command.......................................................................... 3-20 3.6.4 Reading the Statistical Data (.ndat) File ................................................................................................. 3-21

CHAPTER 4 Data Files .............................................................................................................................................................. 4-1

4.1 Introduction ..................................................................................................................................................... 4-1 4.2 Overview of Data Files.................................................................................................................................... 4-1

4.2.1 File Format ............................................................................................................................................... 4-1 4.2.2 Naming Conventions ................................................................................................................................ 4-2

4.2.2.1 Example: Naming Data Files That Save Sequence Measurement Data ............................................ 4-3 4.2.2.2 Example: Naming Data Files That Save Immediate Measurement Data........................................... 4-3

4.2.3 Active Data Files ...................................................................................................................................... 4-4 4.2.4 Template Files .......................................................................................................................................... 4-4

4.3 Types of Data Files.......................................................................................................................................... 4-5 4.3.1 Sample Measurement Data Files .............................................................................................................. 4-5

4.3.1.1 Measurement Data Files .................................................................................................................... 4-6 4.3.1.2 Scan Data Files .................................................................................................................................. 4-6 4.3.1.3 Raw Data Files................................................................................................................................... 4-7 4.3.1.4 Diagnostic Data Files......................................................................................................................... 4-7

4.3.2 Helium Data File ...................................................................................................................................... 4-7 4.3.3 Environment Log Files ............................................................................................................................. 4-7 4.3.4 Field Profile Scan Files............................................................................................................................. 4-8 4.3.5 EDC Data Files......................................................................................................................................... 4-8

4.4 Data File Management..................................................................................................................................... 4-9 4.4.1 Creating a Measurement Data File ........................................................................................................... 4-9

4.4.1.1 Creating a Measurement Data File to Save Immediate Measurement Data ...................................... 4-9


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4.4.1.2 Creating a Measurement Data File to Save Sequence Measurement Data ...................................... 4-10 4.4.1.3 Creating a Measurement Data File within a Sequence .................................................................... 4-10

4.4.2 Creating an Environment Log File ......................................................................................................... 4-11 4.4.3 Changing the Sequence Base Data File Name........................................................................................ 4-12 4.4.4 Creating a Graph Template File ............................................................................................................. 4-13 4.4.5 Applying a Graph Template File ............................................................................................................ 4-13 4.4.6 Printing a Graph ..................................................................................................................................... 4-13

4.5 Data-Viewing Formats .................................................................................................................................. 4-14 4.5.1 Graph View ............................................................................................................................................ 4-14 4.5.2 Record View........................................................................................................................................... 4-15 4.5.3 Table View ............................................................................................................................................. 4-16 4.5.4 Raw Data View....................................................................................................................................... 4-16

4.6 Graph Formats ............................................................................................................................................... 4-17 4.6.1 Selecting Gridlines and Data Indicators ................................................................................................. 4-17 4.6.2 Plotting Parameters................................................................................................................................. 4-18 4.6.3 Magnifying a Graph ............................................................................................................................... 4-19 4.6.4 Restoring the Current Graph Configuration File .................................................................................... 4-19 4.6.5 Restoring the Default Graph Format ...................................................................................................... 4-19

CHAPTER 5 Sequence Files ..................................................................................................................................................... 5-1

5.1 Introduction ..................................................................................................................................................... 5-1 5.2 Overview of Sequence Files ............................................................................................................................ 5-1

5.2.1 Sequence Commands................................................................................................................................ 5-1 5.2.2 Sequence Command Bar........................................................................................................................... 5-2 5.2.3 Sequence Editor........................................................................................................................................ 5-2 5.2.4 Naming Conventions ................................................................................................................................ 5-3 5.2.5 Selected Sequence and Active Sequence.................................................................................................. 5-3

5.3 Sequence File Management............................................................................................................................. 5-4 5.3.1 Creating a Sequence ................................................................................................................................. 5-4 5.3.2 Editing a Sequence ................................................................................................................................... 5-4 5.3.3 Modifying Command Parameters within a Sequence............................................................................... 5-5 5.3.4 Printing a Sequence .................................................................................................................................. 5-5 5.3.5 Locking Sequence Status.......................................................................................................................... 5-6 5.3.6 Unlocking Sequence Status ...................................................................................................................... 5-6

5.4 Running a Sequence: An Example .................................................................................................................. 5-7 5.4.1 Prepare for the Measurement.................................................................................................................... 5-8 5.4.2 Create the Sequence.................................................................................................................................. 5-8 5.4.3 Select the Data File................................................................................................................................... 5-9 5.4.4 Run the Sequence ................................................................................................................................... 5-10

5.4.4.1 Pausing, Resuming, or Aborting a Sequence Run........................................................................... 5-10 5.4.4.2 Viewing Data Files .......................................................................................................................... 5-10

5.5 Running a Partial Sequence........................................................................................................................... 5-11 5.6 Editing a Paused Sequence Run .................................................................................................................... 5-11


iv MPMS MultiVu Application User’s Manual Quantum Design

CHAPTER 6 Sequence Commands ....................................................................................................................................... 6-1

6.1 Introduction ..................................................................................................................................................... 6-1 6.2 Overview of Sequence Commands.................................................................................................................. 6-1

6.2.1 End Sequence Command.......................................................................................................................... 6-2 6.2.2 Similarities between Sequence Commands and Menu Options................................................................ 6-2 6.2.3 Guide to Location of Commands in Chapter ............................................................................................ 6-3

6.2.3.1 System Commands ............................................................................................................................ 6-3 6.2.3.2 Center Commands ............................................................................................................................. 6-3 6.2.3.3 Measure Commands .......................................................................................................................... 6-3 6.2.3.4 Bridge Channel Diagnostic Commands............................................................................................. 6-3 6.2.3.5 Calibration Factor Diagnostic Commands......................................................................................... 6-4 6.2.3.6 Chamber Diagnostic Commands ....................................................................................................... 6-4 6.2.3.7 Driver Channel Diagnostic Commands ............................................................................................. 6-4 6.2.3.8 Magnet Diagnostic Commands.......................................................................................................... 6-5 6.2.3.9 SQUID Diagnostic Commands.......................................................................................................... 6-5 6.2.3.10 Data Logging Commands ................................................................................................................ 6-5 6.2.3.11 Transport Diagnostic Commands .................................................................................................... 6-5 6.2.3.12 Voltmeter Diagnostic Commands.................................................................................................... 6-6

6.3 Scan Commands .............................................................................................................................................. 6-7 6.3.1 Operation of Control Loop ....................................................................................................................... 6-7 6.3.2 End Scan Command ................................................................................................................................. 6-8

6.4 System Commands .......................................................................................................................................... 6-9 6.4.1 Move Sample............................................................................................................................................ 6-9

6.4.1.1 Movement Modes ............................................................................................................................ 6-10 6.4.2 Remark ................................................................................................................................................... 6-10 6.4.3 Run Sequence ......................................................................................................................................... 6-10 6.4.4 Scan Field ............................................................................................................................................... 6-10

6.4.4.1 Spacing Modes ................................................................................................................................ 6-11 6.4.4.2 Steps Modes..................................................................................................................................... 6-12 6.4.4.3 Approach Modes ............................................................................................................................. 6-12 6.4.4.4 Resolution Modes ............................................................................................................................ 6-12

6.4.5 Scan Rotation.......................................................................................................................................... 6-13 6.4.5.1 Spacing Modes ................................................................................................................................ 6-13 6.4.5.2 Steps Modes..................................................................................................................................... 6-14

6.4.6 Scan Temperature ................................................................................................................................... 6-14 6.4.6.1 Spacing Modes ................................................................................................................................ 6-15 6.4.6.2 Steps Modes..................................................................................................................................... 6-15 6.4.6.3 Approach Modes ............................................................................................................................. 6-15

6.4.7 Set Field.................................................................................................................................................. 6-16 6.4.8 Set Temperature Undercool.................................................................................................................... 6-16 6.4.9 Set Temperature...................................................................................................................................... 6-16 6.4.10 Wait For................................................................................................................................................ 6-17

6.5 Center Commands ......................................................................................................................................... 6-18 6.5.1 Adjust Position ....................................................................................................................................... 6-18 6.5.2 DC Center ............................................................................................................................................... 6-18 6.5.3 DC Parameters........................................................................................................................................ 6-18

6.5.3.1 EMU Modes .................................................................................................................................... 6-19 6.5.4 Full DC Scan .......................................................................................................................................... 6-19 6.5.5 Initialize Transport ................................................................................................................................. 6-19

6.6 Measure Commands ...................................................................................................................................... 6-20 6.6.1 Measure DC............................................................................................................................................ 6-20 6.6.2 Set Datafile ............................................................................................................................................. 6-21

6.7 Diagnostic Commands................................................................................................................................... 6-21


Quantum Design MPMS MultiVu Application User’s Manual v

6.7.1 Bridge Channels Commands .................................................................................................................. 6-21 6.7.1.1 Autorange ........................................................................................................................................ 6-21 6.7.1.2 Autoscan .......................................................................................................................................... 6-22 6.7.1.3 Max Excitation ................................................................................................................................ 6-22 6.7.1.4 User Mode ....................................................................................................................................... 6-22

6.7.2 Calibration Factor Commands................................................................................................................ 6-22 6.7.2.1 Magnet............................................................................................................................................. 6-22 6.7.2.2 SQUID............................................................................................................................................. 6-23 6.7.2.3 Field Penetration.............................................................................................................................. 6-23 6.7.2.4 SQUID Extended Range.................................................................................................................. 6-23 6.7.2.5 SQUID Regression .......................................................................................................................... 6-23 6.7.2.6 Minimum Data Points...................................................................................................................... 6-23 6.7.2.7 Transverse Rotator Steps/Degree .................................................................................................... 6-23 6.7.2.8 SQUID Settle Time ......................................................................................................................... 6-23 6.7.2.9 Temperature Tolerance.................................................................................................................... 6-24 6.7.2.10 Low Temperature .......................................................................................................................... 6-24 6.7.2.11 Fill Temperature ............................................................................................................................ 6-24 6.7.2.12 Fill Time ........................................................................................................................................ 6-24 6.7.2.13 Fill Power ...................................................................................................................................... 6-24 6.7.2.14 Oven Factor ................................................................................................................................... 6-24 6.7.2.15 Maximum Temperature ................................................................................................................. 6-24 6.7.2.16 Minimum Warming Rate ............................................................................................................... 6-25 6.7.2.17 Maximum Rate on Pot ................................................................................................................... 6-25 6.7.2.18 Low-Temperature Heater Factor ................................................................................................... 6-25 6.7.2.19 Reservoir Fill ................................................................................................................................. 6-25 6.7.2.20 Thermometer Consistency Tolerance ............................................................................................ 6-25 6.7.2.21 Inductance...................................................................................................................................... 6-26 6.7.2.22 Charge Rate ................................................................................................................................... 6-26 6.7.2.23 Quench Time ................................................................................................................................. 6-26 6.7.2.24 Cool Time...................................................................................................................................... 6-26

6.7.3 Chamber Commands .............................................................................................................................. 6-26 6.7.3.1 Cooling Valve.................................................................................................................................. 6-26 6.7.3.2 Flush Valve...................................................................................................................................... 6-26 6.7.3.3 Impedance Heater ............................................................................................................................ 6-27 6.7.3.4 Level Meter...................................................................................................................................... 6-27 6.7.3.5 Start Valve Sequence....................................................................................................................... 6-27 6.7.3.6 Valve Sequencing ............................................................................................................................ 6-28 6.7.3.7 Valve/Heater Select ......................................................................................................................... 6-28 6.7.3.8 Vent Valve....................................................................................................................................... 6-28

6.7.4 Driver Channels Commands................................................................................................................... 6-28 6.7.4.1 Assigned Input................................................................................................................................. 6-28 6.7.4.2 Balance Point................................................................................................................................... 6-29 6.7.4.3 Feedback Mode ............................................................................................................................... 6-29 6.7.4.4 Maximum Power ............................................................................................................................. 6-29 6.7.4.5 Minimum Power .............................................................................................................................. 6-29 6.7.4.6 Output Range................................................................................................................................... 6-30 6.7.4.7 Output Power................................................................................................................................... 6-30 6.7.4.8 PID Differentiator............................................................................................................................ 6-30 6.7.4.9 PID Gain.......................................................................................................................................... 6-30 6.7.4.10 PID Integrator ................................................................................................................................ 6-31 6.7.4.11 PID Preset ...................................................................................................................................... 6-31 6.7.4.12 Updates .......................................................................................................................................... 6-31


vi MPMS MultiVu Application User’s Manual Quantum Design

6.7.5 Magnet Commands................................................................................................................................. 6-31 6.7.5.1 Charging Mode................................................................................................................................ 6-31 6.7.5.2 High-Resolution Mode .................................................................................................................... 6-32 6.7.5.3 High-Resolution Relay .................................................................................................................... 6-32 6.7.5.4 Magnet Current................................................................................................................................ 6-32 6.7.5.5 Magnet Power.................................................................................................................................. 6-32 6.7.5.6 Magnet Relay................................................................................................................................... 6-33 6.7.5.7 Magnet Reset ................................................................................................................................... 6-33 6.7.5.8 Switch Heater .................................................................................................................................. 6-33 6.7.5.9 Update Magnetic Field .................................................................................................................... 6-33

6.7.6 SQUID Commands................................................................................................................................. 6-33 6.7.6.1 Auto Reset ....................................................................................................................................... 6-33 6.7.6.2 Group Reset ..................................................................................................................................... 6-33 6.7.6.3 Select Mode ..................................................................................................................................... 6-34 6.7.6.4 Select Power .................................................................................................................................... 6-34 6.7.6.5 Select Tune ...................................................................................................................................... 6-34 6.7.6.6 SQUID Filter ................................................................................................................................... 6-34 6.7.6.7 SQUID Gain .................................................................................................................................... 6-34 6.7.6.8 SQUID Heater ................................................................................................................................. 6-34 6.7.6.9 SQUID Quench ............................................................................................................................... 6-34 6.7.6.10 SQUID Range................................................................................................................................ 6-35 6.7.6.11 SQUID Reset ................................................................................................................................. 6-35

6.7.7 Data Logging Commands ....................................................................................................................... 6-35 6.7.7.1 Start Data Logging........................................................................................................................... 6-35 6.7.7.2 Stop Data Logging........................................................................................................................... 6-35

6.7.8 Transport Commands ............................................................................................................................. 6-35 6.7.8.1 Auto Tracking.................................................................................................................................. 6-36 6.7.8.2 Calibrate Long ................................................................................................................................. 6-36 6.7.8.3 Calibrate Rotator.............................................................................................................................. 6-36 6.7.8.4 Define Long..................................................................................................................................... 6-36 6.7.8.5 Move Long ...................................................................................................................................... 6-36 6.7.8.6 Move Rotator................................................................................................................................... 6-37 6.7.8.7 Rotate to Zero .................................................................................................................................. 6-37 6.7.8.8 Set Long Acceleration ..................................................................................................................... 6-37 6.7.8.9 Set Long Initial Rate........................................................................................................................ 6-37 6.7.8.10 Set Long Power ............................................................................................................................. 6-37 6.7.8.11 Set Long Slew................................................................................................................................ 6-37 6.7.8.12 Stop Rotator................................................................................................................................... 6-38

6.7.9 Voltmeter Commands............................................................................................................................. 6-38 6.7.9.1 Readings to Average........................................................................................................................ 6-38 6.7.9.2 Sampling Rate.................................................................................................................................. 6-38 6.7.9.3 Set Gain ........................................................................................................................................... 6-38


Quantum Design MPMS MultiVu Application User’s Manual vii

CHAPTER 7 System Operations ............................................................................................................................................ 7-1

7.1 Introduction ..................................................................................................................................................... 7-1 7.2 Setting the Temperature................................................................................................................................... 7-1 7.3 Setting the Magnetic Field............................................................................................................................... 7-2 7.4 Controlling the Chamber Atmosphere............................................................................................................. 7-3 7.5 Tuning the SQUID .......................................................................................................................................... 7-3 7.6 Monitoring Helium Transfers .......................................................................................................................... 7-5 7.7 Entering Standby Mode................................................................................................................................... 7-5 7.8 Advanced System Operations.......................................................................................................................... 7-6

7.8.1 Correcting the Field-Intensity Data .......................................................................................................... 7-6 7.8.2 Resetting the Magnet ................................................................................................................................ 7-6 7.8.3 Logging Data Parameters ......................................................................................................................... 7-6 7.8.4 Reviewing Calibration Factors ................................................................................................................. 7-7 7.8.5 Configuring the Message Display .......................................................................................................... 7-10 7.8.6 Logging Events....................................................................................................................................... 7-11 7.8.7 Installing and Activating Options........................................................................................................... 7-12 7.8.8 Converting MPMSR2 DOS Files ........................................................................................................... 7-12

CHAPTER 8 Diagnostics............................................................................................................................................................ 8-1

8.1 Introduction ..................................................................................................................................................... 8-1 8.2 Overview of Diagnostics ................................................................................................................................. 8-1 8.3 Bridge Channel Diagnostics ............................................................................................................................ 8-2 8.4 Chamber Diagnostics....................................................................................................................................... 8-3 8.5 Driver Channel Diagnostics............................................................................................................................. 8-5 8.6 GPIB Diagnostics ............................................................................................................................................ 8-7

8.6.1 Viewing GPIB Activity ............................................................................................................................ 8-7 8.6.2 Sending GPIB Commands........................................................................................................................ 8-7

8.7 Magnet Diagnostics ......................................................................................................................................... 8-8 8.8 Serial Port Diagnostics .................................................................................................................................... 8-9 8.9 SQUID Diagnostics ....................................................................................................................................... 8-10 8.10 Transport Diagnostics.................................................................................................................................. 8-11 8.11 Voltmeter Diagnostics ................................................................................................................................. 8-14 8.12 Temperature Control.................................................................................................................................... 8-15

APPENDIX A Installation Instructions................................................................................................................................. A-1

A.1 Introduction ................................................................................................................................................... A-1 A.2 Overview of Installation ................................................................................................................................ A-1

A.2.1 Configuration Files and the Machine State............................................................................................. A-1 A.3 Installing MPMS MultiVu............................................................................................................................. A-2

A.3.1 Install the GPIB Software....................................................................................................................... A-2 A.3.2 Install the GPIB Board............................................................................................................................ A-2 A.3.3 Install MPMS MultiVu ........................................................................................................................... A-2 A.3.4 Change the EPROMs.............................................................................................................................. A-3 A.3.5 Update the Calibration Files ................................................................................................................... A-3 A.3.6 Set the SQUID Drive and Tune Levels .................................................................................................. A-3


viii MPMS MultiVu Application User’s Manual Quantum Design

APPENDIX B Data File Format................................................................................................................................................B-1

B.1 Introduction.....................................................................................................................................................B-1 B.2 Overview of Data File Format ........................................................................................................................B-1 B.3 Data File Header .............................................................................................................................................B-2 B.4 Data Section....................................................................................................................................................B-3

B.4.1 Data Section Field Names in Each Type of Data File..............................................................................B-3 B.5 Data Types ......................................................................................................................................................B-5

B.5.1 Numerical Data ........................................................................................................................................B-5 B.5.2 Strings ......................................................................................................................................................B-5 B.5.3 Boolean ....................................................................................................................................................B-5 B.5.4 Additional Information ............................................................................................................................B-5

References..............................................................................................................................................References-1 Index ................................................................................................................................................................ Index-1

Contents Table of Figures

Quantum Design MPMS MultiVu Application User’s Manual ix

Figures Figure 1-1. System Startup Dialog Box...................................................................................................................1-3 Figure 2-1. MPMS MultiVu Interface.....................................................................................................................2-2 Figure 2-2. Control Center ......................................................................................................................................2-6 Figure 2-3. Status Bar Maximized...........................................................................................................................2-7 Figure 3-1. Correctly Positioned Sample.................................................................................................................3-2 Figure 3-2. Sample Transport and Electronic Control Assembly............................................................................3-3 Figure 3-3. O-Rings on Socket Block Assembly.....................................................................................................3-4 Figure 3-4. Sample Description Dialog Box ...........................................................................................................3-5 Figure 3-5. DC Centering Dialog Box.....................................................................................................................3-7 Figure 3-6. DC Center Parameters Dialog Box .......................................................................................................3-8 Figure 3-7. DC Centering Measurement and Measured SQUID Voltage Response.............................................3-10 Figure 3-8. Adjust Sample Position Dialog Box ...................................................................................................3-11 Figure 3-9. Measure DC Dialog Box.....................................................................................................................3-12 Figure 3-10. MPMS MultiVu Window, Sequence Commands Panel and New Sequence File ...........................3-18 Figure 3-11. Multiple Measurement Dialog Box Set Up to Perform RSO Measurements....................................3-18 Figure 3-12. Measure RSO Dialog Box for Setting Measurement Parameteres ...................................................3-19 Figure 3-13. Multiple Measurement Command Dialog Box After the Advanced Button has been selected ........3-19 Figure 3-14. MPMS MultiVu Window Showing Control Center Panel, Sequence Commands, and Sequence File06 Chapter 3.doc ..............................................................3-21 Figure 3-15. Contents of the Statistical Data File for Record #10 of QuartzVR1.rso...........................................3-22 Figure 4-1. General Tab in Log Data Dialog Box.................................................................................................4-11 Figure 4-2. Standard Items Tab in Log Data Dialog Box......................................................................................4-12 Figure 4-3. Graph View.........................................................................................................................................4-14 Figure 4-4. Record View .......................................................................................................................................4-15 Figure 4-5. Table View..........................................................................................................................................4-16 Figure 4-6. Plot Appearance Dialog Box ..............................................................................................................4-17 Figure 4-7. Data Selection Dialog Box .................................................................................................................4-18 Figure 5-1. Sequence Command Bar.......................................................................................................................5-2 Figure 5-2. Sequence Editor ....................................................................................................................................5-3 Figure 5-3. Lock Sequence Dialog Box ..................................................................................................................5-6 Figure 5-4. Status Information Appearing in Control Center While Sequence Runs..............................................5-7 Figure 5-5. Example Sequence File.........................................................................................................................5-9 Figure 5-6. Run Sequence Pop-up Dialog Box .....................................................................................................5-11 Figure 5-7. Sequence Status Dialog Box Shown While Running Sequence Is Paused.........................................5-11 Figure 5-8. Sequence Editor Showing Example of Command List Sequence File ...............................................5-12 Figure 6-1. Illustration of Control Loop in Sequence Editor...................................................................................6-7 Figure 6-2. Move Transport Dialog Box.................................................................................................................6-9 Figure 6-3. Scan Field Dialog Box........................................................................................................................6-11 Figure 6-4. Scan Rotation Dialog Box ..................................................................................................................6-13 Figure 6-5. Scan Temperature Dialog Box............................................................................................................6-14 Figure 6-6. Wait For Dialog Box ..........................................................................................................................6-17 Figure 6-7. DC Center Parameters Dialog Box .....................................................................................................6-18 Figure 6-8. Measure DC Dialog Box for Sequence Measurement ........................................................................6-20

Contents Table of Figures

x MPMS MultiVu Application User’s Manual Quantum Design

Figure 7-1. Temperature Parameters Dialog Box 7-1 Figure 7-2. Magnetic Field Dialog Box...................................................................................................................7-2 Figure 7-3. Chamber Dialog Box ............................................................................................................................7-3 Figure 7-4. SQUID Tuning Dialog Box Showing Longitudinal Tab ......................................................................7-3 Figure 7-5. Helium Fill Status Screen .....................................................................................................................7-5 Figure 7-6. General Tab in Log Data Dialog Box...................................................................................................7-6 Figure 7-7. Standard Items Tab in Log Data Dialog Box........................................................................................7-7 Figure 7-8. Configure Error Handling Dialog Box ...............................................................................................7-10 Figure 7-9. Event Log ...........................................................................................................................................7-11 Figure 7-10. Configure Logging Dialog Box ........................................................................................................7-11 Figure 8-1. Bridge Channel Diagnostics Dialog Box..............................................................................................8-2 Figure 8-2. Chamber/Gas Control Diagnostics Dialog Box....................................................................................8-3 Figure 8-3. Bridge Driver Diagnostics Dialog Box.................................................................................................8-5 Figure 8-4. GPIB Status Dialog Box.......................................................................................................................8-7 Figure 8-5. Send GPIB Commands Dialog Box......................................................................................................8-7 Figure 8-6. Magnet Diagnostics Dialog Box...........................................................................................................8-8 Figure 8-7. Monitor Communication Port Dialog Box ...........................................................................................8-9 Figure 8-8. Longitudinal Tab in SQUID Diagnostics Dialog Box........................................................................8-10 Figure 8-9. Sample Transport Tab in Transport Diagnostics Dialog Box.............................................................8-12 Figure 8-10. Motor Configuration Dialog Box .....................................................................................................8-13 Figure 8-11. Voltmeter Diagnostics Dialog Box...................................................................................................8-14 Figure 8-12. Temperature Control Dialog Box .....................................................................................................8-15

Contents Table of Tables

Quantum Design MPMS MultiVu Application User’s Manual xi

Tables Table 1-1. New Features in MPMS MultiVu ..........................................................................................................1-2 Table 2-1. MPMS MultiVu Menus..........................................................................................................................2-3 Table 2-2. MPMS MultiVu Tool Bar Buttons.........................................................................................................2-4 Table 2-3. Equivalent Tool Bar Button and Menu Commands ...............................................................................2-5 Table 2-4. Data in Sequence Status Panels..............................................................................................................2-7 Table 2-5. Data in Field Status Panels.....................................................................................................................2-8 Table 2-6. Data in Temperature Status Panels.........................................................................................................2-8 Table 2-7. Data in Chamber Status Panels ..............................................................................................................2-9 Table 3-1. Sample Parameters .................................................................................................................................3-5 Table 3-2. Scan Parameters .....................................................................................................................................3-6 Table 3-3. SQUID Parameters.................................................................................................................................3-6 Table 3-4. Summary of Functions of Measurement Algorithms ...........................................................................3-15 Table 4-1. Components of Data File Names ...........................................................................................................4-2 Table 4-2. File Extensions .......................................................................................................................................4-2 Table 4-3. Name and Function of Data File Types .................................................................................................4-5 Table 6-1. Suggested Use of Field Approach Modes............................................................................................6-12 Table 6-2. Suggested Use of Temperature Approach Modes................................................................................6-15 Table 6-3. System Conditions Affected by Wait For Command...........................................................................6-17 Table 6-4. Operating Modes for Impedance Heater ..............................................................................................6-27 Table 6-5. Maximum Output Range......................................................................................................................6-30 Table 6-6. Magnet Polarity Modes ........................................................................................................................6-32 Table 6-7. Reset Modes for SQUID ......................................................................................................................6-35 Table 7-1. Suggested Use of Field Approach Modes..............................................................................................7-2 Table 7-2. Standard MPMS Calibration Factors .....................................................................................................7-8 Table 7-3. Default Values for Standard MPMS Calibration Factors.......................................................................7-9 Table 7-4. System Messages .................................................................................................................................7-10 Table 8-1. Physical Channel Control Parameters ....................................................................................................8-3 Table 8-2. Settings for Gas System .........................................................................................................................8-4 Table 8-3. Driver Control Settings ..........................................................................................................................8-6 Table 8-4. Control Parameters Settings ...................................................................................................................8-6 Table 8-5. Magnet Control Parameters....................................................................................................................8-8 Table 8-6. SQUID Control Commands .................................................................................................................8-10 Table 8-7. Movement Control Commands ............................................................................................................8-12 Table 8-8. Motor Configuration Parameters..........................................................................................................8-13 Table 8-9. Voltmeter Diagnostic Parameters.........................................................................................................8-14

Quantum Design MPMS MultiVu Application User’s Manual xiii

P R E F A C E

Contents and Conventions

P.1 Introduction This preface contains the following information:

! Section P.2 discusses the overall scope of the manual.

! Section P.4 illustrates and describes conventions that appear in the manual.

! Section P.3 briefly summarizes the contents of the manual.

P.2 Scope of the Manual This manual discusses the MPMS MultiVu application, which is the software running the Magnetic Property Measurement System (MPMS) and the MPMS options. This manual describes how you install and how you use MPMS MultiVu.

The MPMS MultiVu application must run on Windows 95. This manual assumes you are familiar with Windows 95.

For information about the MPMS hardware, refer to the MPMS Hardware Reference Manual. For specific information about any of the MPMS options, refer to the appropriate option manual.

P.3 Contents of the Manual ! Chapter 1 introduces the MPMS MultiVu

application. ! Chapter 4 discusses MPMS MultiVu

data files. ! Chapter 2 discusses the MPMS MultiVu

interface. ! Chapter 5 discusses MPMS MultiVu

sequence files and sequence operation. ! Chapter 3 explains how to use MPMS

MultiVu to take a sample measurement. ! Chapter 6 discusses MPMS MultiVu

sequence commands.

Section P.4 Preface Conventions in the Manual Contents and Conventions

xiv MPMS MultiVu Application User’s Manual Quantum Design

! Chapter 7 explains how to use MPMS MultiVu to perform basic system operations.

! Appendix A explains how to install MPMS MultiVu.

! Chapter 8 explains how to use MPMS MultiVu to perform diagnostic functions.

! Appendix B explains the format of MPMS MultiVu data files.

P.4 Conventions in the Manual File menu Bold text distinguishes the names of menus, options, buttons, and panels appearing

on the PC monitor.

File!Open The ! symbol indicates that you select multiple, nested software options.

.dat The Courier font distinguishes code and the names of files and directories.

<Enter> Angle brackets distinguish the names of keys located on the PC keyboard.

<Alt+Enter> A plus sign connecting the names of two or more keys distinguishes keys you press simultaneously.

A pointing hand introduces a supplementary note.

An exclamation point inside an inverted triangle introduces a cautionary note.

A lightning bolt inside an inverted triangle introduces a warning.

Quantum Design MPMS MultiVu Application User’s Manual 1-1

C H A P T E R 1

Introduction to MPMS MultiVu

1.1 Introduction This chapter contains the following information:

! Section 1.2 presents an overview of the MPMS MultiVu application.

! Section 1.3 explains how to start up MPMS MultiVu.

1.2 Overview of the MPMS MultiVu Application MPMS MultiVu is a 32-bit, Windows 95"based application that controls and monitors the operation of the MPMS hardware and the operation of installed MPMS options. MPMS MultiVu integrates all system operations into one versatile and easy-to-use Windows 95 interface (see figure 2-1). System operation is simplified; multiple commands that open files, run measurements, or set parameters are always enabled. The control center and status bar in the MPMS MultiVu interface always display status information.

MPMS MultiVu functions like any Windows 95 application and uses all Windows 95 conventions. Windows 95 utilities may be used to control and manage MPMS MultiVu file folders without exiting MPMS MultiVu. MPMS MultiVu may run simultaneously with other applications.

NOTE

This manual generally describes one method of performing a specific task in MPMS MultiVu. However, different MPMS MultiVu commands can often be used to perform the identical task. As you work with MPMS MultiVu, you will discover multiple ways of performing identical tasks.

1.2.1 Immediate Mode and Sequence Mode Operation MPMS MultiVu supports manual, or immediate, tasks and automated, or sequence, tasks. Menu options and control center commands execute immediately. Sequence commands execute only when the sequence file in which the commands are included runs, but while the sequence runs, the commands are executed automatically. If you select a measurement command in the MPMS MultiVu

Section 1.2 Chapter 1 Overview of the MPMS MultiVu Application Introduction to MPMS MultiVu

1-2 MPMS MultiVu Application User’s Manual Quantum Design

Measure menu, you are taking a measurement in immediate mode. If you add a measurement sequence command to a sequence file and then run the sequence, you are taking a measurement in sequence mode.

1.2.2 Data Viewing MPMS MultiVu offers tremendous flexibility in data-viewing options. When you open a data file, you see a plot of the actual data stored in the file. You can modify the appearance of the graph view of the file and select which types of data are plotted in the graph. You can also use tables or a text editor to examine the data, and you can import the data file into another graphics application. MPMS MultiVu automatically saves all system-generated data to data files.

1.2.3 Comparison with the MPMSR2 DOS Software MPMS MultiVu simplifies many of the tasks performed in the MPMSR2 DOS software and includes new features that make it easier to work with the MPMS.

Table 1-1. New Features in MPMS MultiVu

TASK

WHAT MPMS MULTIVU DOES

MANUAL REFERENCE

Storing Data Stores data in data files and prevents data files from being overwritten. Allows data files to be opened at any time.

Section 4.2 Section 4.3

Viewing Data Allows graph of data file to be modified and data to be examined in different viewing formats.

Section 4.5 Section 4.6

Automating Operation Edits, executes, and controls sequence files. Section 5.2 Section 5.4

Recording Events Includes event log that records error, information, and sequence events.

Section 7.8.6

Recording System Data Includes environment log file that can store system data indefinitely.

Section 4.3.3

Tuning SQUID Allows SQUID coils to be tuned automatically. Section 7.5

Running Control Loop Includes scan sequence commands that create execution loops.

Section 6.3

Performing Diagnostics Includes Diagnostics dialogs that list all diagnostic parameters and allow parameters to be modified.

Chapter 8

MPMS MultiVu allows you to convert MPMSR2 DOS sequence files and data files to the MPMS MultiVu format.

!# Select the Utilities!Convert Sequence menu option to convert an MPMSR2 DOS sequence. !# Select the Utilities!Convert Data File menu option to convert an MPMSR2 DOS data file.

Chapter 1 Section 1.3 Introduction to MPMS MultiVu Starting Up MPMS MultiVu


1.3 Starting Up MPMS MultiVu 1. Do one of the following: (a) select the MPMS MultiVu icon that is on the desktop or (b) open

the Windows 95 Start menu and then locate and select the MPMS MultiVu option. The MPMS MultiVu option may be located in the Programs!Quantum Design folder.

2. Wait for MPMS MultiVu to start up. The MPMS MultiVu interface opens, and in the center of the interface, the System Startup dialog box appears. The System Startup dialog box identifies each task the system performs as part of start-up. The dialog box disappears as soon as start-up is complete.

Figure 1-1. System Startup Dialog Box


C H A P T E R 2

MPMS MultiVu Interface


! Section 2.2 summarizes the function of the MPMS MultiVu interface.

! Section 2.3 discusses the main features of the MPMS MultiVu interface.

2.2 Function of the MPMS MultiVu Interface Menu options and command buttons in the MPMS MultiVu interface perform all manual and automated MPMS tasks. Immediate instrument status feedback information displayed in the interface indicates the current system status. The interface allows immediate control of the MPMS for performing a wide variety of standard tasks, such as changing the temperature or magnetic field, running measurements, or logging system data. The interface also allows most functions of the MPMS and the MPMS options to be automated by using a series of simple commands, called a sequence. MPMS MultiVu provides the sequence editor and the commands that initiate and control the running sequence.

The MPMS MultiVu interface simplifies data collection and data viewing. Data can be viewed in a graphic, tabular, or raw data format. Data can be viewed in real time during automated operation, or it can be viewed after it has been collected.

2.2.1 MDI Application Interface MPMS MultiVu is a multiple document interface (MDI) Windows application. In MPMS MultiVu, multiple documents may be open for viewing and editing at any one time, and a single document can be viewed in multiple ways. For example, a data file can be viewed in a graph, table, record, or raw data window. Each different view presents the same information in a unique manner. The name of the active document appears in the title bar of the main MPMS MultiVu window. To activate a document, you simply click anywhere within its window.

Section 2.3 Chapter 2 Features of the MPMS MultiVu Interface MPMS MultiVu Interface


2.3 Features of the MPMS MultiVu Interface The MPMS MultiVu menu options and command buttons provide multiple ways of performing many basic tasks, such as opening files and running sequences. The menu options and command buttons that are available depend on the active file and the task being performed and also on the installed hardware options. Figure 2-1 illustrates the basic elements of the MPMS MultiVu interface. Other windows may be visible, depending on the task being performed.

Figure 2-1. MPMS MultiVu Interface

Tool Bar

Control Center

Status Bar

Sequence Editor

Graph View of Data File

Chapter 2 Section 2.3 MPMS MultiVu Interface Features of the MPMS MultiVu Interface


2.3.1 Menu Bar All MPMS MultiVu functions are accessible through the menus in the menu bar. The available menus and menu options vary, based on the current task, active file, and installed MPMS options. Some options add items to the menus.

Table 2-1. MPMS MultiVu Menus

MENU FUNCTION

File Contains standard Windows commands that create, open, or close files.

Edit Contains standard Windows editing commands that edit sequence files. Menu is available only when sequence file is active.

View Options show or hide parts of interface or select data-viewing formats.

Sample Options summarize sample parameter and sample installation data.

Sequence Options control sequence operation.

Center Options control centering operation.

Measure Options control measurement operation.

Graph Options open and modify graph configuration files and create and apply graph template files.

Instrument Options control basic operation of MPMS hardware.

Utilities Options are tools that help operate MPMS or are diagnostics that directly control MPMS hardware.

Window Contains standard Windows organization commands that arrange icons or windows. Menu is available only when sequence or data file is active.

Help Standard Windows Help menu.

2.3.2 Pop-up Menus In addition to the menus in the menu bar, MPMS MultiVu includes a Graph pop-up menu and an Edit pop-up menu, which provide shortcuts to data-viewing commands and editing commands, respectively. The Graph pop-up menu is available only when the graph view of a data file is active. The Edit pop-up menu is available only when a sequence file is active.

You open the Graph pop-up menu by right-clicking the mouse inside a graph window. If you right-click anywhere inside the graph window except immediately above or below the graph, then all menu options, including X Axis Auto Scale and Y Axis Auto Scale, are available.

Graph pop-up menu options and Graph menu options are nearly identical. Options in both menus modify graph configuration files and create and apply graph template files. However, Graph pop- up menu options emphasize modifying the graph format and selecting data-viewing formats. Graph menu options emphasize opening and saving files.

You open the Edit pop-up menu by right-clicking the mouse inside a sequence editor window. Edit pop-up menu options and Edit menu options are identical. Both menus contain standard Windows editing commands that you apply to sequence files.



2.3.3 Tool Bar The tool bar buttons provide shortcuts that let you initiate many of the more frequently performed MPMS MultiVu functions without having to select multiple, nested menu options. The buttons are grouped according to function. The active file and the current state of sequence operation determine which buttons are enabled.

You may move, resize, dock, hide, or display the tool bar. The View!Tool Bar toggle option hides or displays the tool bar.

If the mouse pointer pauses over a tool bar button, a ToolTip pops up to display the name of the button.

Table 2-2. MPMS MultiVu Tool Bar Buttons

BUTTON FUNCTION

New Sequence File Creates and opens new sequence file by opening sequence

editor window for file.

Open Sequence File Opens sequence file by opening sequence editor window

for file.

Save Sequence File Saves active sequence file. Button is enabled only when

sequence file is active.

Open Graph File Opens data file whose graph format is defined by selected

graph configuration file.

Open Data File Opens data file.

Cut Removes command or commands selected in sequence

file. Button is enabled only when sequence file is active.

Copy Copies command or commands selected in sequence file.

Button is enabled only when sequence file is active.

Paste

Pastes last cut or copied command or commands into sequence file. Button is enabled only when sequence file is active.

Print Prints active sequence file or graph view of active data file.

About Identifies which version of MPMS MultiVu is running.

Run Sequence Runs selected sequence. Button is enabled only when

sequence status is unlocked and no sequence is running.

Pause Sequence Resume Sequence

Pauses or resumes unlocked sequence run. Button is enabled only when unlocked sequence runs.

Abort Sequence Aborts unlocked sequence run. Button is enabled only

when unlocked sequence runs.

Lock\Unlock Sequence Locks or unlocks current sequence status.



Table 2-3. Equivalent Tool Bar Button and Menu Commands

TOOL BAR BUTTON

EQUIVALENT MENU COMMAND

New Sequence File File!New Sequence

Open Sequence File File!Open!Sequence

Save Sequence File File!Save

Open Graph File File!Open!Graph

Open Data File File!Open!DataFile

Cut Edit!Cut

Copy Edit!Copy

Paste Edit!Paste

Print File!Print

About Help!About

Run Sequence Sequence!Control!Run

Pause Sequence Sequence!Control!Pause

Resume Sequence Sequence!Control!Resume

Abort Sequence Sequence!Control!Abort

Lock Sequence Sequence!Control!Options!Lock

Unlock Sequence Sequence!Control!Options!Unlock



2.3.4 Control Center The control center summarizes sequence status information and allows you to control sequence operation without having to select menu options. The status panels and command buttons in the control center are grouped according to function and are arranged, from top to bottom, in the order you normally review or select them.

The Sample panel at the top of the control center displays the name of the sample. You select the Sample Change button to review or redefine the sample parameters.

The Selected Sequence panel displays the name of the selected sequence, which is the sequence file that runs the next time an MPMS MultiVu Run command is issued. The Edit button opens the selected sequence, and the Selected Sequence Change button lets you choose another sequence to run.

The Sequence Base Data File Name panel displays the base name of the data files that will store the sequence measurement data. The View button opens the graph view of one of these files. The Sequence Base Data File Name Change button lets you select another data file to store the measurement data.

The Sequence Status panel indicates the status of the selected sequence$Idle, Running, or Paused$and when the sequence runs, displays (1) the command line number, as indicated in the sequence editor, and name of the sequence command being executed; (2) the name of the running sequence; and (3) the base name of the active data files. Clicking once in the Sequence Status panel opens the Sequence Status dialog box.

Run and Abort buttons as well as Pause or Resume and Lock or Unlock toggle buttons are at the bottom of the control center.

The View!Control Center toggle option hides or displays the control center. Clicking once on any sequence status panel in the MPMS MultiVu status bar (see section 2.3.5.1) also displays the control center. You may move or dock the control center.

Figure 2-2. Control

Center



2.3.5 Status Bar The status bar displays the sequence status and the status of the magnetic field, system temperature, and MPMS sample chamber. Panels displaying the same type of information are grouped together.

You may minimize, maximize, hide, display, or move the status bar. By default, the status bar is maximized to show the maximum amount of status information. The View!Status Bar!Minimum option minimizes the status bar so that it shows a minimal amount of information. View!Status Bar!None hides the status bar. View!Status Bar!Maximum displays the entire status bar.

Each field, temperature, and chamber status panel in the status bar is also a command button that opens the Magnetic Field, Temperature Parameters, or Chamber dialog box, respectively. These dialog boxes display status information and let you change the system state.

Figure 2-3. Status Bar Maximized

2.3.5.1 SEQUENCE STATUS PANELS

The sequence status panels indicate whether a sequence is running. The top or first panel always indicates the sequence status: Idle, Running, or Paused. During the run, the sequence status panels display the name of the running sequence and the base name of the active data files. If another sequence is selected for editing while a sequence is running, the sequence status panels continue to show the name of the running sequence and the base name of the data files storing the measurement data from the current sequence run.

Clicking once on any sequence status panel displays the control center.

Table 2-4. Data in Sequence Status Panels

DISPLAYED DATA

PANEL STATUS BAR MAXIMIZED STATUS BAR MINIMIZED

Top or Left

! Sequence status: “Idle,” “Running,” or “Paused”

! Sequence name and status during sequence run

! “none” and “Idle” if sequence is idle

Middle or Right

! Sequence name during sequence run ! “none” if sequence is idle

! Data file name if sequence is running ! “none” if sequence is idle

Bottom ! Data file name if sequence is running ! “none” if sequence is idle

Sequence Status Panels

Field Status Panels

Temperature Status Panels

Chamber Status Panels



2.3.5.2 FIELD STATUS PANELS

The field status panels display the current magnetic field and indicate the state of field control.

Clicking once on any field status panel opens the Magnetic Field dialog box.

Table 2-5. Data in Field Status Panels

DISPLAYED DATA


Top Field set point Current field and state of field control

Middle Current field

Bottom State of field control

2.3.5.3 TEMPERATURE STATUS PANELS

The temperature status panels display the current system temperature and indicate the state of temperature control.

Clicking once on any temperature status panel opens the Temperature Parameters dialog box.

Table 2-6. Data in Temperature Status Panels

DISPLAYED DATA


Top Current system temperature Current system temperature and state of temperature control

Middle Temperature set point and sweep rate

Bottom State of temperature control



2.3.5.4 CHAMBER STATUS PANELS

The chamber status panels display the state of the sample chamber status and indicate the level of helium in the dewar.

Clicking once on any chamber status panel opens the Chamber dialog box.

Table 2-7. Data in Chamber Status Panels

DISPLAYED DATA


Top Helium level in dewar Helium level in dewar

Middle State of sample chamber

Bottom Status of impedance heater, driver, and cooling valve

When the EverCool option is active, the MPMS MultiVu status bar can display EverCool system status data instead of sample chamber status data. Refer to the Magnetic Property Measurement System: EverCool Dewar Option User’s Manual.

2.3.6 Data File Windows MPMS MultiVu documents include data files. You may examine data files in graph, table, record, or raw data windows. You may move, minimize, and maximize these windows. Any number of these windows may be open at one time.

Chapter 4 discusses data files and data-viewing formats in detail.

2.3.7 Sequence Windows MPMS MultiVu documents include sequence files. A sequence editor window displays the sequence commands and command parameters comprising one sequence file. The sequence command bar displays all available sequence commands. Any number of sequence editor windows may be open at one time. You may move, minimize, or maximize the sequence editor window. You may edit a sequence within the sequence editor window. You may move, dock, hide, or display the sequence command bar.

Chapter 5 discusses sequence files and sequence operation in detail.


C H A P T E R 3

Sample Measurement


! Section 3.2 presents an overview of the sample measurement process.

! Section 3.4 describes the measurement algorithms.

! Section 3.3 explains how to take a DC sample measurement in immediate mode.

! Section 3.5 discusses factors to consider when performing a measurement.

3.2 Overview of Sample Measurements MPMS MultiVu measures the magnetic moment of a sample by reading the output of the SQUID detector while the sample moves upward, from the initialization position, through the SQUID pickup coils. This upward movement through the SQUID pickup coils completes one vertical scan. Voltage readings that are taken as a function of the sample’s position in the coils comprise the raw measure-ment data. At each position in the coils, MPMS MultiVu typically reads the SQUID output voltage several times, and MPMS MultiVu can average together multiple scans in order to improve the measurement resolution. MPMS MultiVu saves the raw measurement data to the active raw data, or .raw, file. After collecting the raw voltages, MPMS MultiVu computes the magnetic moment of the sample and saves the magnetic moment to the active measurement data, or .dat, file.

The magnetic moment calibration for the MPMS is determined by measuring a palladium standard over a range of magnetic fields and by then adjusting the system calibration factors to obtain the correct moment for the standard. The standard is a right circular cylinder approximately 3 mm in diameter % 3 mm in height. Due to the geometry of the SQUID pickup coils, samples of this size or smaller are effectively point sources to an accuracy of approximately 0.1%.

Section 3.3 Chapter 3 Measuring the Sample Sample Measurement


3.3 Measuring the Sample The procedures in this section explain how you use the standard sample transport to perform a manual, or immediate, DC sample measurement. Section 5.4 explains how you automate DC measurements by running a sequence. The Magnetic Property Measurement System: AC Option User’s Manual explains how you perform an AC sample measurement. The Magnetic Property Measurement System: Reciprocating Sample Option User’s Manual explains how you perform an RSO sample measurement and how you use the RSO sample transport.

3.3.1 Attach the Sample The type, size, and geometry of a sample determine the method you use to attach it to the sample rod. This section explains how you use a clear plastic drinking straw to attach a sample. The straw has minimal magnetic susceptibility and is thus a useful means of attaching a sample. The MPMS Hardware Reference Manual describes other techniques you can use to attach samples.

Complete the following steps to attach the sample to the sample rod:

1. Cut off a small section of a clear plastic drinking straw. The section must be small enough to fit lengthwise inside the straw.

2. Weigh and measure the sample. After you insert the sample into the sample chamber, you can use the Sample!Description option to define the sample’s mass, in milligrams, and its diameter and length, in millimeters.

3. Use phenolic tweezers to place the sample inside the small straw segment. 4. Hold the straw segment so that its two

open ends are vertical. 5. Place the straw segment inside the drink-

ing straw, and move the segment until it is in approximately the middle of the length of the straw. Verify that the walls of the straw obstruct the open ends of the segment. Refer to figure 3-1.

6. Wrap a sufficient amount of tape around the brass-colored end of the sample rod so that the drinking straw will fit snugly over the rod. Quantum Design recommends using Kapton tape.

7. Place the end of the drinking straw over the tape on the sample rod, and then use additional tape to securely attach the straw to the rod.

8. Place a small piece of tape over the exposed end of the drinking straw. This extra piece of tape prevents a loose sample from falling into the sample chamber.

9. Move the slide seal plug up and down part of the sample rod to verify that the rod is well lubricated. If the plug does not move easily, apply a small amount of Apiezon H Grease to the rod. Run your fingers along the length of the rod to ensure a light, even coating of grease.

Figure 3-1. Correctly Positioned Sample

Chapter 3 Section 3.3 Sample Measurement Measuring the Sample


3.3.2 Insert the Sample 1. Turn the airlock lever on the electronic control assembly counterclockwise so that it is horizontal

and in the “Closed” position (see figure 3-2). The MPMS vents the airlock space, which is the portion of the sample chamber located above the airlock valve. When the airlock lever is closed, it closes the airlock value that is near the top of the sample chamber, thus protecting the lower portion of the chamber from air flowing into the top of the chamber.

Figure 3-2. Sample Transport and Electronic Control Assembly

2. Wait for the MPMS to vent the airlock space. The yellow “Venting” LED (figure 3-2) flashes on and off while the system vents the space and remains off when the space is vented. The green “Ready” LED does not turn on.

3. Push the two slide seal clamps on the socket block assembly (see figures 3-2 and 3-3) so that the handles of the clamps face the front of the MPMS. When the clamp handles face the front of the MPMS, the airlock plug is unlocked and may be removed from the opening of the airlock space.

4. Remove the airlock plug, which has an anodized, blue coating. Store the plug in a safe place.



5. Verify that three O-rings are on top of the socket block assembly (see figure 3-3). If necessary, stand on a stool or small ladder so that you can examine the top of the socket block. Reinsert any missing O-rings. The large O-ring at the mouth of the airlock space occasionally sticks to the sample rod when the rod is removed from the sample chamber.

WARNING

Never insert the sample rod into the sample chamber if the O-rings on the top of the socket block assembly are missing. The O-rings prevent air from pumping into the chamber. Air pumped into the chamber can damage the vacuum pump and freeze the sample.

Figure 3-3. O-Rings on Socket Block Assembly

6. Move the slide seal plug down the sample rod until the plug rests just above the sample holder. 7. Lower the sample rod into the airlock space. 8. Move the slide seal plug down the sample rod until the plug rests on top of the socket block

assembly. If necessary, adjust the position of the slide seal clamps to correctly seat the plug. 9. Turn the slide seal plug until the white dot on the plug faces the front of the MPMS. When the

white dot faces the front of the MPMS, the proper amount of gas flows through the slide seal. 10. Push the two slide seal clamps completely outward or inward. When the handles of the clamps

do not face the front of the MPMS, the clamps lock the slide seal plug in position by forcing it downward against the three O-rings.

11. Press the “Purge Airlock” button on the electronic control assembly (see figure 3-2). The MPMS purges the airlock space and cycles through the purge sequence four times. The yellow “Venting” LED turns on during the purge.

12. Wait for the MPMS to purge the airlock space. The green “Ready” LED turns on when the purge sequence is complete. If the “Ready” LED does not turn on, the airlock space may have a leak. Missing or improperly seated O-rings may cause the leak. Perform the following steps to check for a leak: (a) Select Instrument!Chamber!Vent Sample Space to vent the sample chamber; (b) remove the sample rod when the “Venting” LED turns off; and (c) verify that the O-rings are properly seated and lubricated. If necessary, correctly seat and lubricate the O-rings.



13. Turn the airlock lever clockwise so that it is vertical and in the “Open” position. When the lever is in the “Open” position, it opens the airlock value.

14. Lower the sample rod gently and slowly until the black slide clamp on the rod engages the actuator shoe on top of the sample transport. Figure 3-2 illustrates the actuator shoe. When the slide clamp engages the actuator shoe, the rod is fully inserted into the sample chamber. The knurled nut must be near the top of the sample rod or you will be unable to fully insert the rod into the sample chamber. If necessary, loosen the nut, and then move it until it is 1 to 2 inches from the top of the rod.

15. Loosen the two clip screws on top of the actuator shoe until the screw threads are visible. Do not remove the screws.

16. Rotate the slide clamp so that its two curved slots hook around the clip screws. If necessary, continue to loosen the clip screws until the slide clamp is properly seated.

17. Tighten the clip screws. The clip screws secure the sample rod to the actuator shoe, so the sample transport can move the rod vertically.

3.3.3 Define the Sample Parameters Table 3-1. Sample Parameters

PARAMETER

ACCEPTED VALUES

DEFAULT VALUE

Mass 0"10,000 mg 1 mg

Diameter 0"9 mm 1mm

Defining the sample parameters is optional; MPMS MultiVu does not read the parameters during the measurement. However, if you want to save the parameters to a measurement data file, you must define them before specify-ing the base name of the data file and before running the measurement. MPMS MultiVu saves sample parameter data to a data file header only while creating the data file. Length 0"100 mm 1 mm

Complete the following steps to define the sample parameters:

1. Select Sample!Description. The Sample Description dialog box opens.

2. Verify that the Sample Installed check box is selected. If necessary, click once on the check box.

3. Enter a descriptive name for the sample. Unknown is the default name until a name is specified. The name you enter is the name under which MPMS MultiVu stores all information about the sample and the measurement.

4. Enter the mass, in milligrams, of the sample. 5. Enter the diameter, in millimeters, of the sample. 6. Enter the length, in millimeters, of the sample. 7. Define the shape of the sample. 8. Enter a comment if you want to include a com-

ment in the data file header. A comment may have up to 63 characters.

9. Select OK.

Figure 3-4. Sample Description Dialog Box



3.3.4 Center the Sample The sample must be centered in the SQUID pickup coils to ensure that all four coils sense the magnetic moment of the sample. If the sample is not centered, the coils read only part of the magnetic moment.

The MPMS can run a full DC centering measurement or a partial DC centering measurement. System operation during a full centering measurement is factory defined; the MPMS scans the entire length of the sample transport’s vertical travel path, and MPMS MultiVu reads the maximum number of data points. System operation during a partial centering measurement is defined by the values you set for the scan and SQUID parameters. During a partial centering measurement, the MPMS scans only the distance you specify, and MPMS MultiVu reads only the number of data points you specify.

The parameter values set for a partial centering measurement are set for any subsequent sample mea-surements. A partial centering measurement therefore indicates whether the sample will be centered during the sample measurement. Before you measure the sample, you should run a partial centering measurement.

Table 3-2. Scan Parameters

ACCEPTED VALUES

PARAMETER CENTERING SCAN FULL SCAN DEFINITION

Scan Length 0.1"12 cm 12 cm Length of sample transport’s vertical travel path that is scanned. Sample is centered when it is in middle of scan length.

Data Points 2"64 64 Individual voltage readings plot-ting response curve in centering scan data file.

Autotracking Enabled Disabled

Enabled Disabled

Automatic tracking and adjustment of sample position to keep sample centered in SQUID coils. Auto-tracking compensates for thermal expansion and contraction in sample rod.

Table 3-3. SQUID Parameters

ACCEPTED VALUES

PARAMETER CENTERING SCAN FULL SCAN DEFINITION

Measurement Axis

Longitudinal Transverse

Longitudinal SQUID axis from which measure-ments are taken.

EMU Range Autoranging Normal Extended

Autoranging Normal Extended

Autoranging allows EMU range to be changed as necessary so that it is appropriate for SQUID output. EMU range is sensitivity value indicating maximum magnetic moment MPMS can measure with-out saturating SQUID detector.

Sections 3.3.4.1 through 3.3.4.4 explain how you center the sample.



3.3.4.1 INITIALIZE THE SAMPLE TRANSPORT

1. Select Center!DC. The DC Centering dialog box opens. The Status panel at the top of the dialog box indicates the status of an on-going centering measurement and the result of the last centering measurement. The Control panel contains the centering command buttons. The function of each button is summarized to the right of the button.

Figure 3-5. DC Centering Dialog Box

2. Select Initialize Transport. The MPMS initializes, or calibrates, the sample transport by first lowering it to the lower-travel-limit switch, which is defined as zero, and then raising it until it is in a known position that is just above the lower-travel-limit switch. When the transport is in this known position, it is correctly located to begin centering the sample. The initialization position places the sample far enough below the pickup coils that the SQUID does not detect the sample moment. If autotracking is enabled when you initialize the transport, the MPMS initializes the transport by moving it to a position far enough above the lower-travel-limit switch in order to allow adjust-ments for any shrinkage that occurs in the sample rod. This position corresponds to a 0.5-cm offset when the sample chamber is at room temperature. To enable autotracking, select Center! DC!Parameters!Autotracking. Refer to section 3.3.4.2 below.



3.3.4.2 DEFINE THE PARAMETERS

1. Select Parameters in the DC Centering dialog box. The DC Center Parameters dialog box opens and displays the value of each scan and SQUID parameter MPMS MultiVu uses during a partial centering measurement.

Figure 3-6. DC Center Parameters Dialog Box

2. Enter the length, in centimeters, of the scan. The default length of a partial centering measure-ment is 6 cm. During a full centering measurement, the MPMS scans the complete travel path, which is 12 cm.

3. Enter the number of data points that MPMS MultiVu reads during the scan. The default number of data points read during a partial centering measurement is 32. During a full centering mea-surement, MPMS MultiVu reads the maximum number of data points, which is 64.

4. Verify that autotracking is enabled. If necessary, click once on the Autotracking check box.

NOTE

Disable autotracking only if you are working with a sample that is very sensitive to centering or if you are using a custom-built sample rod. Quantum Design used a normal sample rod and a quartz sample holder to develop the sample-tracking algorithms. Sample holders and rods that respond to temperature differently than brass, steel, or quartz exhibit greater variations in the position of the sample.

5. Select the SQUID axis from which MPMS MultiVu takes measurements. The Transverse axis option is enabled only if the Transverse SQUID is installed. During a full centering measure-ment, MPMS MultiVu uses the longitudinal SQUID axis.

6. Verify that autoranging is enabled. If necessary, click once on the Use Autoranging check box.

NOTE

Disable autoranging only if you know the sample’s approximate EMU value and you want to define the normal or extended EMU range most closely matching that value. The Extended EMU range option is enabled only if the Extended Range (EDR) option is installed.

7. Select OK. The DC Center Parameters dialog box closes, and the DC Centering dialog box appears again.



3.3.4.3 RUN THE CENTERING MEASUREMENT

1. Select Full DC Scan or Center in the DC Centering dialog box. !# Full DC Scan runs a full centering measurement, which covers the complete length of the

sample transport’s travel path. A full centering measurement always locates the sample. !# Center runs a partial centering measurement. A partial centering measurement locates the

sample only if the sample is within the section of the travel path that is scanned. As soon as you initiate the centering measurement, the sample transport moves upward, carrying the sample through the pickup coils. While the sample moves through the coils, MPMS MultiVu measures the SQUID’s response to the magnetic moment of the sample and saves all data from the centering measurement to the centering scan data, or center.dc.lastscan, file. Status messages appearing at the top of the DC Centering dialog box identify the specific task MPMS MultiVu is performing. Figure 3-7 on the following page illustrates the progress of a centering measurement. During a partial centering measurement, MPMS MultiVu uses the iterative regression algorithm to calculate the magnetic moment of the sample. During a full centering measurement, MPMS MultiVu uses the full scan algorithm. If the iterative regression algorithm cannot center the signal, MPMS MultiVu substitutes the linear regression algorithm. The centering measurement continues uninterrupted. Section 3.4 discusses the measurement algorithms in detail. When the centering measurement is complete, the Moment box in the DC Centering dialog box displays the new sample moment, and the Center Position box indicates the sample’s new position. The center.dc.lastscan file opens as a graph that plots the SQUID’s voltage response and the regression fit to that response against the length of the scan.

2. Examine the plot of the center.dc.lastscan file to determine whether the sample is centered in the SQUID pickup coils. Refer to figure 3-7. The sample is centered when the peak of the large, middle curve is within 0.05 cm of the half-way point of the scan length. In a 6-cm scan, for example, the sample is centered when the peak of the middle curve is within 0.05 cm of the 3-cm point. The shape of the plot is a function of the geometry of the pickup coils. The coils are wound in a second-derivative configuration in which the single-turn, positively charged upper and lower coils are counterwound with respect to the two-turn, negatively charged center coil. In the plot, the large, middle curve is the reading from the two center coils. The smaller first and third curves are the readings from the first and fourth coils, respectively. The second-derivative configuration strongly rejects interference from nearby magnetic sources and lets the MPMS function without a superconducting shield around the pickup coils.

3. Select Full DC Scan if the MPMS just ran a partial centering measurement but did not locate the sample. After the full centering measurement runs, examine the plot of the center.dc .lastscan file. Refer to step 2.

4. Select Center if the MPMS just ran a full centering measurement or has not yet run a partial centering measurement. After the partial centering measurement runs, examine the plot of the center.dc.lastscan file. Refer to step 2.

You may abort a centering measurement at any time. Simply select the Abort button located at the bottom of the DC Centering dialog box. After the measurement aborts, Measurement aborted appears in the Status panel at the top of the dialog box.



Figure 3-7. DC Centering Measurement and Measured SQUID Voltage Response

Figure 3-7a illustrates the sample moving upward through the SQUID pickup coils. Figure 3-7b illustrates MPMS MultiVu measuring the SQUID response while the sample moves through the coils. Figure 3-7c plots the SQUID response against the scan length; the output in figure 3-7c indicates that the sample is too high and must be lowered. Figure 3-7d illustrates a centered sample. In figure 3-7d, the scan begins one-half scan length below the center coils.



3.3.4.4 ADJUST THE SAMPLE POSITION

1. Select Adjust Position in the DC Centering dialog box if the sample is not centered in the SQUID pickup coils. Adjust Position opens the Adjust Sample Position dialog box.

Figure 3-8. Adjust Sample Position Dialog Box

2. Enter, in centimeters, the correct position of the sample if the computed position displayed in the Sample Location text box is incorrect.

3. Verify that the Perform scan after adjustment check box is selected. If necessary, click once on the check box.

4. Select Adjust Automatically. The MPMS adjusts the position of the sample so that the center peak of the SQUID’s voltage response is within 0.1 cm of half the length of the scan. The MPMS then runs a partial centering measurement. A plot of the center.dc.lastscan file opens when the centering measurement is complete. If automatic adjustment is outside the limits of the transport mechanism and the RSO option is not installed, a pop-up message tells you to adjust the position manually. Select Adjust Manually in the Adjust Sample Position dialog box and then follow the on-screen instructions.

!# Lower the sample if the peak of the large, middle curve in the center.dc.lastscan file is to the left of the half-way point of the scan length.

!# Raise the sample if the peak is to the right of the half-way point of the scan length. 5. Select Close, and then select Close again to close the DC Centering dialog box.



3.3.5 Measure the Sample When you initiate an immediate-mode measurement, MPMS MultiVu measures the sample at the current system conditions without waiting for any conditions to stabilize. If you want to ensure that system conditions are stable when the measurement begins, run the measurement in a sequence and use appropriate sequence commands to stabilize system conditions. Refer to section 5.4.

Sections 3.3.5.1 through 3.3.5.3 explain how you run a measurement in immediate mode. Before running a measurement, you may want to refer to section 3.5, “Measurement Considerations.”

3.3.5.1 DEFINE THE PARAMETERS

1. Select Measure!DC. The Measure DC dialog box opens. The Status panel at the top of the dialog box indicates the status of an on-going measurement and the result of the last measure-ment. The Control panel lists the scan and SQUID parameters MPMS MultiVu uses during a measurement and identifies which data files will store the measurement data. Table 3-2 defines the scan parameters. Table 3-3 defines the SQUID parameters.

CAUTION

Avoid radically modifying the scan and SQUID parameters before you run the sample measurement. By using identical parameter values for the partial centering measurement and the sample measurement, you help ensure that the sample remains centered and that the partial centering measurement accurately reflects the conditions of the sample measurement.

Figure 3-9. Measure DC Dialog Box

2. Enter the length, in centimeters, of the scan if the specified scan length is inappropriate for the measurement.

3. Enter the number of scans that MPMS MultiVu runs and averages together. The MPMS can run from 1 to 50 scans. Specify a large number if the sample is data sensitive or has an extremely small signal. Specify a small number if the sample or experiment is time sensitive. A large number of scans, by including changes that occur in the data, produces more reliable data. When two or more scans run as part of one measurement, MPMS MultiVu computes the average sample moment and standard deviation of each scan and then averages the values of the scans.



4. Enter the number of data points that MPMS MultiVu reads during the scan if the specified number is inappropriate for the measurement. The data points plot the response curve appearing in the active measurement data, or .dat, file.

5. Verify that autotracking is enabled. If necessary, click once on the Autotracking check box.

NOTE

Disable autotracking only if you are working with a sample that is very sensitive to centering or if you are using a custom-built sample rod. Quantum Design used a normal sample rod and a quartz sample holder to develop the sample-tracking algorithms. Sample holders and rods that respond to temperature differently than brass, steel, or quartz exhibit greater variations in the position of the sample.

6. Select the SQUID axis from which MPMS MultiVu takes measurements. The Transverse axis option is enabled only if the Transverse SQUID option is installed.

7. Select the measurement algorithm MPMS MultiVu uses to calculate the magnetic moment of the sample. Section 3.4 discusses the measurement algorithms in detail.

8. Verify that autoranging is enabled. If necessary, click once on the Use Autoranging check box.

NOTE

Disable autoranging only if you know the sample’s approximate EMU value and you want to define the normal or extended EMU range most closely matching that value. The Extended EMU range option is enabled only if the Extended Range (EDR) option is installed.

3.3.5.2 SELECT THE DATA FILES

1. Select Change if you want to save measurement data to a file other than the measurement data, or .dat, file currently selected to store immediate-mode measurement data. The name of the selected .dat file appears in the Data File panel, which is to the left of the Change button. Change opens the Select or Enter a New DC Data File dialog box. The dialog box lists the names of all .dat files. You can select a file and then select Open, or you can enter the base name of a file in the File name text box, and then select Open. The full name of the .dat file you select or create appears in the Data File panel. You must create a new .dat file if you want to save the sample parameter data you entered in section 3.3.3 to a .dat file. MPMS MultiVu saves sample parameter data to a data file header only while creating the .dat file. Consequently, there may not be an existing data file containing sample parameter data identifying your sample. If you want to append data to an existing .dat file, try to select a file whose header information identifies your sample.

2. Verify that the Include Diagnostics Data check box is selected if you want to save diagnostic measurement data to a diagnostic data, or .diag, file. If necessary, click once on the check box.

3. Verify that the Include Raw Data check box is selected if you want to save raw measurement data to a raw data, or .raw, file. If necessary, click once on the check box.



3.3.5.3 RUN THE MEASUREMENT

To run a measurement, select Measure in the Measure DC dialog box. The measurement begins. The sample transport moves upward, carrying the sample through the pickup coils. While the sample moves through the coils, MPMS MultiVu measures the SQUID’s response to the magnetic moment of the sample. If autoranging is disabled, the MPMS repeats each measurement until it locates the EMU range that accommodates the SQUID’s sensitivity. MPMS MultiVu saves all data from the measure-ment to the active data files. Status messages appearing at the top of the Measure DC dialog box identify the specific task MPMS MultiVu is performing.

If the iterative regression algorithm is selected but iterative regression cannot center the signal, MPMS MultiVu substitutes the linear regression algorithm. The measurement continues uninterrupted.

When the measurement is complete, the Moment box in the Measure DC dialog box displays the new sample moment, and the Standard Deviation box displays the new standard deviation.

You may abort a measurement at any time. Simply select the Abort button located at the bottom of the Measure DC dialog box. The measurement aborts as quickly as possible, although it does not abort in the middle of a scan, but waits until the scan is complete. MPMS MultiVu collects all available data from the aborted measurement and stores the data in the active data files. After the measurement aborts, Measurement aborted appears in the Status panel at the top of the Measure DC dialog box.

3.3.5.4 VIEW THE DATA FILES

Selecting the View button in the Measure DC dialog box can open any data file that is selected to store the immediate-mode measurement data. View opens the Select a Data File dialog box. By default, the dialog box lists the names of only the files that are either actively storing measurement data or that will store data the next time a measurement runs. The files share the identical base name. When you select a data file, and then select the Open button, the graph view of the data file opens.

You may open a new data file you have selected to store immediate-mode measurement data even before you run a measurement. If you specify a new base file name and then select the View button, MPMS MultiVu creates the .dat file and the file’s associated .lastscan file. MPMS MultiVu also creates the .diag and .raw files if you have selected the Include Diagnostics Data and Include Raw Data options. All the new files are blank; they contain only the header information, which defines the default graph format. Once you open a new file, you can modify the default graph format. New files remain blank until you run a measurement.

Chapter 3 Section 3.4 Sample Measurement Measurement Algorithms


3.4 Measurement Algorithms After MPMS MultiVu collects the raw measurement data, it uses a measurement algorithm to compute the sample’s magnetic moment. Three measurement algorithms are available: iterative regression, linear regression, and full scan. The algorithms should work effectively if MPMS MultiVu collects 24 data points during the scan, although MPMS MultiVu can collect up to 64 data points.

Table 3-4 summarizes the operation of the measurement algorithms and indicates when you should use each algorithm. The following sections discuss the algorithms in more detail.

Table 3-4. Summary of Functions of Measurement Algorithms

ALGORITHM DEFINITION WHEN TO USE

Iterative Regression Calculates magnetic moment by mathematically fitting analytical curve to measurement response data. Default measurement algorithm during partial centering measurement.

! To perform short, high-precision scans with few data points.

! To perform fast measurements that are relatively insensitive to noise and drift.

! To measure very small, noisy, or off-center signals.

Linear Regression Calculates magnetic moment by mathematically fitting analytical curve to measurement response data and by assuming sample is properly centered. Used during partial centering measurement if iterative regression cannot center signal.

! To perform short, high-precision scans with few data points.

! To measure very small, noisy, or off-center signals.

Full Scan Calculates magnetic moment by building response curve as sample moves through full length of pickup coils and by then computing weighted summation of all points in scan. Default measurement algorithm during full centering measurement.

! To perform full centering measurement.

! To locate sample within pickup coils.

3.4.1 Iterative Regression Algorithm The iterative regression algorithm calculates the magnetic moment of the sample by mathematically fitting an analytical curve to the measurement response data. By fitting the curve to the data, the iterative regression algorithm can accommodate variations in the sample’s position that are caused by the thermal expansion of the sample rod. The use of an analytical curve also allows short, high-precision scans that have relatively few data points. The iterative regression algorithm thus permits fast measurements that are less sensitive to noise and drift than measurements performed with the full scan algorithm.

Section 3.4 Chapter 3 Measurement Algorithms Sample Measurement


The iterative regression algorithm is the default measurement algorithm during a partial centering measurement. MPMS MultiVu substitutes the linear regression algorithm only if the iterative regression algorithm cannot center the signal. Iterative regression cannot locate the signal if the signal is beyond a certain tolerance.

During a measurement, you select the iterative regression algorithm if you require short, high-precision scans with few data points, or if you require fast measurements that are relatively insensitive to noise and drift. You also select the iterative regression algorithm if you are measuring very small, noisy, or off-center signals. You should avoid selecting the iterative regression algorithm if the scan length includes most of the sample transport’s travel path. Iterative regression$because it tries to fit data to an ideal curve$has difficulty calculating the sample moment when the scan length is large.

3.4.2 Linear Regression Algorithm The linear regression algorithm calculates the magnetic moment of the sample by mathematically fitting an analytical curve to the measurement response data and by assuming the sample is properly centered. The use of an analytical curve allows short, high-precision scans that have relatively few data points. Regression calculations eliminate noise effectively. The linear regression algorithm thus permits fast measurements that are less sensitive to noise and drift than measurements performed with the full scan algorithm. MPMS MultiVu substitutes the linear regression algorithm if the iterative regression algorithm cannot center the signal.

During a measurement, you select the linear regression algorithm if you require short, high-precision scans with few data points, or if you are measuring very small, noisy, or off-center signals.

3.4.3 Full Scan Algorithm The full scan algorithm calculates the magnetic moment of the sample by building a response curve as the sample moves through the full length of the SQUID pickup coils and by then computing a weighted summation of all points in the scan. The sample moment is computed as the square root of the sum of the squares, normalized for the number of data points and the system calibration factors. This analysis works well when the signal is larger than the noise in the system. However, when the response of the sample is comparable to the system noise, the full scan algorithm, because of its squaring process, effectively sums the system noise as well as the sample response instead of trying to average the noise to zero.

The full scan algorithm is the default measurement algorithm during a full centering measurement. The MPMS always locates the sample during a full scan, so MPMS MultiVu never substitutes another algorithm while a full scan is in progress.

During a measurement, you select the full scan algorithm if the MPMS will perform a full scan of the sample transport’s travel path, or if the MPMS has not located the sample within the pickup coils. You select the iterative regression algorithm or linear regression algorithm instead of the full scan algorithm if you are measuring very small, noisy, or off-center signals. The full scan algorithm does not analyze very small signals as effectively as the iterative regression and linear regression algorithms.

Chapter 3 Section 3.6 Sample Measurement Multiple Measure Sequence Command


3.5 Measurement Considerations If a single scan takes too long, low-frequency drifts, which degrade the data, occur in the SQUID detector. Consequently, you should average together several short scans rather than try to collect a large number of data points during a single, lengthy scan. Quantum Design recommends that you average at least 10 to 12 readings at each point. You want to take as much data as possible during a single scan without unduly extending the time required to complete the scan. An individual reading of the SQUID output takes approximately 5 milliseconds, and it takes approximately 1 second to move the sample and allow the filter in the SQUID electronics to settle. The time required to move the sample can be reduced somewhat, but this reduction does not decrease the filter settling time for the SQUID electronics. The scan length and the number of data points collected determine the spacing between each pair of data points.

Collecting a number of data points that is an integral power of 2 may be advantageous if you anticipate that more unusual data processing may be performed on the raw data at a later date. Using an integral power of 2 for the number of data points may be required when you use Fast Fourier Transform routines. Otherwise, the MPMS has no specific requirement on the number of data points collected.

The values defining the measurement parameters significantly affect the accuracy of a measurement when you measure samples producing signals that are either slightly larger or slightly smaller than the instrument noise. The values defining the measurement parameters affect the accuracy of a measure-ment less significantly when you measure samples producing large signals.

3.6 Multiple Measure Sequence Command A new feature—the Multiple Measure sequence command—has been implemented in revision 1.52 of the MPMS MultiVu software. The Multiple Measure sequence command performs a user-specified number of measurements (of type DC or RSO) and reports the average moment, standard error, and other statistical figures for the population of those measurements. With this command, the user can collect time-dependent statistical measurement data from the MPMS instrument. In addition, the user can set the command to reject measurements that deviate from the average of the overall data set. Thus, the feature allows the user to reject spurious measurements (noise or artifacts) from the data population. Such problem measurements may arise from magnet-flux jumps, external vibrations, and so on, which are most commonly observed when running magnetization versus field loops (see MPMS Application Note #1014-820) while detecting low-moment samples (see MPMS Application Note #1014-822).

3.6.1 Compatibility The Multiple Measure command does not alter the way that the MPMS system performs the actual measurement. It only coordinates the running and collection of the measurement data and the calculation of the statistics for that collection. The statistical data is recorded in a file that is separate from the measurement file. The new data file has the same base name as the measurement data file but the file extension is .ndat (e.g., mydata.dc.ndat). One line item is written to the .ndat file for every Multiple Measure command that is completed.

Section 3.6 Chapter 3 Multiple Measure Sequence Command Sample Measurement


The Multiple Measure command is compatible with the Automated Background Subtraction feature of the MPMS system. However, there are difficulties in using the In Order search method when applying a background data file, because the Multiple Measure command can reject a deviant measurement and collect another as a substitute. Such substitute measurements may not track with the correct data in the background data file. Therefore, it is recommended that the In Order search method not be used with the Multiple Measure command. All other search methods will work properly.

3.6.2 Accessing and Using Multiple Measure Command The Multiple Measure command is a sequence command. Hence, it is located in the Measure Commands section of the Sequence Command bar, which is shown in Figure 3-10. The following section explains how to access and use the Multiple Measure command.

1. In the main MultiVu window, select File >> New Sequence (or Sequence >> New).

2. When the Sequence Command panel opens, click on the plus (+) sign next to the Measure Commands section.

3. When the list of commands appears, double click on the Multiple Measure command. The Multiple Measurement Command dialog box will open (see Figure 3-11).

Figure 3-10. MPMS MultiVu Window, Sequence Commands panel, and new sequence file

The Multiple Measurement Command dialog box is used to specify the Type of measurement to perform and the Number of measurements to be collected.

Figure 3-11. Multiple Measuremeant dialog box set up to perform RSO measurements.



In Figure 3-11, the dialog box is set to perform 10 RSO measurements. Additional specifications can be made by using the Parameters and Advanced buttons on the right side of the dialog box.

Clicking on the Parameters button opens the standard dialog box for the type of measurement you chose. Here you can specify details about the measurements that you want taken.

For example, because the Multiple Measurement Command dialog box in Figure 3-11 is set up for RSO measurements, clicking on the Parameters button produces the Measure RSO dialog box, as shown in Figure 3-12. In this example, a typical RSO measurement will consist of a 4 cm center scan at 1 Hz with 5 cycles per scan and 3 scans per measurement. For every measurement, the usual information will be recorded in the .dat, .raw, and .diag files.

Figure 3-12. Measure RSO dialog box for setting measurement parameters

The Advanced button acts differently. If you click on the Advanced button, the Multiple Measurement Command dialog box (Figure 3-11) expands to show a Measurement Rejection Criteria panel (see Figure 3-13). In this panel you can specify the criteria that will be used to reject individual measurements from the data that is collected. You can set two rejection criteria:

!# the maximum number of measurements that are to be rejected

!# the number of standard deviations that is permitted before a measurement moment is a candidate for rejection

Figure 3-13. Multiple Measurement Command dialog box after the Advanced button has been selected.

Note the Measurement Rejection Criteria panel in the lower half of the window.

For your reference, the Multiple Measurement Command dialog box also shows an estimate (Est. maximum time to complete) of the time that it will take to perform the number of measurements you



specified. This estimate includes the time that will be needed to take any necessary extra measurements.

As depicted in Figure 3-13, the Multiple Measurement Command is set to perform 10 RSO type measurements. The Multiple Measurement Command also is set to reject a maximum of two deviant measurements and to reject measurement values that are more than two standard deviations from the mean.

After the measurements have been completed, the program computes the average (Mbar) and standard deviation (SDM) from the collection of moment values. Next, the program determines the moment value that deviates most from the average. If the value deviates by more than the maximum limit that the user set, that moment value is removed from the array of data. Then the program initiates another RSO measurement, which is added to the collection, and Mbar and SDM are recomputed.

As long as the user-specified number of rejections has not been reached, the program will again determine the most deviant moment value. If the deviant value exceeds the average by more than the specified number of standard deviations, it is rejected, another measurement is made, and Mbar and SDM are recomputed. If necessary, this process continues until the maximum number of data rejections has been reached. The final Mbar and SDM are recorded in the .ndat file.

For the data collected with the settings in Figure 3-13, a maximum of two measurements could be removed, and a measurement would have to be more than two standard deviations larger or smaller than the mean value before it would be rejected.

3.6.3 Checking the Status of a Multiple-Measure Command When a Multiple Measure sequence command is executed, the command continues until the specified number of measurements has been completed.

To see the status of the current sequence command, open the Control Center (View >> Control Center), which appears at the left of the MultiVu window. The Control Center shows whether a command is running or complete; the type of measurement being taken; the sequential number of that measurement; and if extra measurements were taken.

As illustrated in Figure 3-14, the Sample is Unnamed, and the name of the Selected Sequence, Sequence1.seq, is that of the open sequence file.

The Sequence Base Data File Name is TestData1. As each of the 10+ measurements is completed, it is stored in a standard data file named TestData1.rso.dat.



Figure 3-14. MPMS MultiVu window showing Control Center panel (left side), Sequence Commands, and

sequence file

When the Multiple Measurement Command has performed the specified number of measurements and ended, the statistical data will be stored in a data file named TestData1.rso.ndat.

The Sequence Status section of the Control Center shows that the command is "Running"; that RSO measurements are being made; and that the measurement is number 1 of 10 (e.g., MeasRSO 1/10). If one extra (substitute) measurement had been taken, the MeasRSO status reading would be 11/10 (i.e., MeasRSO 11/10).

If a measurement meets the rejection criteria and is removed from the array of data that was used to compute Mbar and SDM, an entry is made in the Event Log:

00:45:13 06/08/01 INFO Rejectable measurement found at position: 1, timestamp: 991986148.703000

00:45:13 06/08/01 INFO Measurement rejected.

The position of the rejected measurement is relative to its order in the data. The timestamp corresponds to the time that is recorded in the measurement .dat file for that measurement.

3.6.4 Reading the Statistical Data (.ndat) File Recall that the Multiple Measure command records the results of a statistical analysis of the population of measurement results into a file that has the base name of the individual measurement data file (.dat), but the statistical data file ends with the .ndat extension.

One data line (or record) is written to the .ndat file for each completed Multiple Measure command. To see the statistical data for the measurements, open the .ndat file and select View >> Record. Figure 3-15 illustrates a data record and its layout. The data fields are defined as follows:



Time: The time stamp corresponding to the completion of the first measurement in the collection

Comment: The measurements, if any, that were deviant and rejected. In the example, the 6th value was rejected, then the 10th value was rejected.

Field: The magnetic field present when the Multiple Measure command started.

Avg. Temperature: The average of all the temperatures for the individual measurements in the collection.

Avg. Moment: The average of all the moment values for the individual measurements in the collection.

Figure 3-15. Contents of the statistical data file for record #10 of quartzVR1.rso. Note the .ndat ending for the file name

Avg. Scan Std. Dev.: The average of all the scan standard deviation values for the individual measurements in the collection

Standard Error: The standard deviation of the individual measurements in the collection from the mean of the population moment (m) values, computed using the following equation:

`S.E. = ])([ 2

11

121

1 &&''

" "n

ii

n

inin mm

Note: This value is not to be confused with the average of the scan standard deviations.

Number of Measurements: The number of measurements (as specified in the Multiple Measurement Command dialog box)

Maximum Num. Meas. to Reject: The maximum number of measurements that could be rejected (as specified in the Multiple Measurement Command dialog box)

Num. Std. Dev. for Reject: The rejection criterion (the allowable number of standard deviations before a measurement is rejected, as specified in the Multiple Measurement Command dialog box). If an individual moment value deviates from the average moment of the collection by more than this value, it will be removed from the collection if the Maximum Num. Meas. to Reject value has not already been reached.

Number Meas. Rejected: The number of individual moment values that were rejected and removed from the collection, causing additional measurements to be taken. This number cannot exceed Maximum Num. Meas. to Reject.



Deviate Meas. Exists: The presence of at least one moment value within the collection that still meets the rejection criterion (exceeds the specified maximum number of standard deviations from the average moment) after the maximum number of moment values has been rejected. Note, the position of this deviant measurement will be listed last in the Comment filed.

RSO Position (Data field 15)—Scans per Measurement (Data field 19): Measurement-specific (DC or RSO) parameters

Delta Temp (K): The difference between the largest and smallest temperatures reported for all the measurements in the collection

Error: The presence of a measurement error for at least one measurement in the collection. If an error is reported for a measurement in the collection, the measurement will be rejected (just as a deviant measurement moment value would be) and the program will perform an additional measurement, unless the Maximum Num. Meas. to Reject has been reached. Errant measurements are rejected from the list before deviant measurement values.

Using ABS: The use of Automated Background Subtraction for the population of measurements.


C H A P T E R 4

Data Files


! Section 4.2 presents an overview of data files.

! Section 4.5 discusses the data-viewing formats.

! Section 4.3 discusses the various types of data files.

! Section 4.6 discusses how to change graph formats.

! Section 4.4 discusses data file management.

4.2 Overview of Data Files Multiple types of data files store all measurable data generated by sample measurements, system parameters, and helium fills. Each type of data file stores a specific type of data. Stored data may be examined in several different data-viewing formats, and the plot of the data may be modified. Every data file opens as a graph. A template automatically saves the graph view of a data file.

Data generated by the measurement options is stored in up to four different data files. This multiple-file storage system is in direct contrast to the single-file storage system used in the MPMSR2 DOS software. By separating the measurement data into several files, MPMS MultiVu allows you to easily import the files into other graphics applications.

Data files storing measurement data cannot be overwritten, and no data file can be deleted from within MPMS MultiVu. To delete a data file, you must open the Windows directory that stores the file, and then delete the file from within that directory.

4.2.1 File Format Every data file consists of two main sections: the header and the data section. The data file header defines the type of data file and the type of data stored in the file as well as the file’s default graph format. Data file headers contain the identical type of information. The data section lists the actual data stored in the file. Data sections list data that is specific to the measurement option that generated the data and to the type of data the file stores.

Section 4.2 Chapter 4 Overview of Data Files Data Files


The format of the data files is designed such that the files may be easily imported by other graphic applications, such as Microsoft Excel. The data file format is comma delimited. Appendix B discusses the data file format in more detail.

4.2.2 Naming Conventions You specify the base name of any data file you want to create. When MPMS MultiVu creates the file, it adds file extensions to the base name. One file extension always identifies which type of data the file stores. When appropriate, a second file extension identifies which type of measurement option generated the data. The generic format of a data file name is thus

BaseName.DataType or BaseName.MeasurementType.DataType.

The addition of the file extensions means that multiple data files may share a base name. When you specify a base name for a new measurement data, or .dat, file, MPMS MultiVu uses that name to create the base names of the other data files that also store data while the new .dat file is active. If the base name of a new .dat file is testdata, MPMS MultiVu saves DC sample measurement data to the testdata.dc.dat file and DC centering scan data to the testdata.dc.lastscan file. The file extensions identify and organize the related files. The file extensions also protect the function of each data file, ensuring that the file stores only the appropriate type of data.

Table 4-1. Components of Data File Names

COMPONENT SIGNIFICANCE

Base Name Defines base data file name and can be shared by multiple data files storing different types of data. Base name is user specified and can be any valid Windows 95 file name.

Measurement Type Indicates type of measurement option generating data. Measurement type is system specified.

Data Type Indicates type of data stored in file. Data type is system specified.

Table 4-2. File Extensions

FILE EXTENSION VALID ENTRIES WHAT ENTRY INDICATES

Measurement Type .dc DC measurement .rso RSO measurement .ac AC measurement .pfl Field-profiling measurement

Data Type .dat Measurement data .lastscan Last scan data .diag Summary data from scans .raw Raw SQUID voltages from scans .env System parameter data

Chapter 4 Section 4.2 Data Files Overview of Data Files


4.2.2.1 EXAMPLE: NAMING DATA FILES THAT SAVE SEQUENCE MEASUREMENT DATA

If you specify a new base data file name called PbtoAu_Test1 and then run a sequence that includes DC measurement commands but no other type of measurement command, MPMS MultiVu creates the following two data files when it finishes taking the first measurement in the sequence run:

PbtoAu_Test1.dc.dat PbtoAu_Test1.dc.lastscan

MPMS MultiVu adds the file extensions to the base file name. By default, the data files reside in the C:\QdMpms\Data directory.

If you specify a new base data file name called PbtoAu_Test2, then modify the DC measurement commands in the selected sequence so that MPMS MultiVu saves diagnostic and raw data, and then run the sequence, MPMS MultiVu creates the following four data files when it finishes taking the first measurement in the sequence run:

PbtoAu_Test2.dc.dat PbtoAu_Test2.dc.diag PbtoAu_Test2.dc.raw PbtoAu_Test2.dc.lastscan

If you specify a new base data file name called PbtoAu_Test3, then modify the selected sequence so that it includes RSO measurement commands, and then run the sequence, MPMS MultiVu creates the following six data files when it finishes taking the first measurement in the sequence run:

PbtoAu_Test3.dc.dat PbtoAu_Test3.dc.diag PbtoAu_Test3.dc.raw PbtoAu_Test3.dc.lastscan PbtoAu_Test3.rso.dat PbtoAu_Test3.rso.lastscan

4.2.2.2 EXAMPLE: NAMING DATA FILES THAT SAVE IMMEDIATE MEASUREMENT DATA

If you specify, in the Measure DC dialog box, a new base data file name called CuMagProperties and then run an immediate DC sample measurement, MPMS MultiVu creates the following two data files when it finishes taking the measurement:

CuMagProperties.dc.dat CuMagProperties.dc.lastscan

When you specify the base file name, MPMS MultiVu adds the file extensions to the name immedi-ately because it knows which type of measurement option will generate the data.

By default, the data files reside in the C:\QdMpms\Data directory.

Section 4.2 Chapter 4 Overview of Data Files Data Files


4.2.3 Active Data Files The active data files are the files actively storing the measurement data as the data is generated. A data file that is selected to store measurement data does not become “active” until a sequence or immediate measurement begins to run. An active file remains active until the sequence or immediate measure-ment is aborted or completes or until MPMS MultiVu reads a Set Datafile sequence command.

MPMS MultiVu identifies the data files that either are active or that will be active. The sequence status panels in the status bar and the Sequence Status panel in the control center display the base name of the files storing sequence measurement data. The Sequence Base Data File Name panel in the control center displays the base name of the files storing sequence measurement data or that will store data the next time a sequence runs. The Data File panel in the Measure dialog box displays the full name of the .dat file storing immediate-mode measurement data or that will store data the next time a measurement runs. Figure 5-4 illustrates the control center. Figure 3-9 illustrates the Measure DC dialog box.

The Set Datafile sequence command instructs MPMS MultiVu to make new data files the active data files. The base name of the new files appears in the Sequence Status panel and the sequence status panels, but does not appear in the Sequence Base Data File Name panel.

4.2.4 Template Files Two types of template files save the defined graph format of data files. A graph configuration, or .gph, file is the template saving the most recently defined graph format of a data file. A graph template, or .tpl, file is a template you create to save the defined graph format of a data file. The graph format is the physical appearance of the graph; that is, the data parameters the graph plots and the gridlines and data indicators the graph uses to plot the data points.

A .gph file is associated with each data file you have opened and then closed. MPMS MultiVu creates the .gph file the first time you close the file. MPMS MultiVu uses the base name of the data file to create the base name of the .gph file. The first time you close the testdata.dc.dat file, MPMS MultiVu creates the testdata.dc.dat.gph file. Every time you reopen and close a data file, MPMS MultiVu updates the associated .gph file. The .gph file ensures that any changes you make to the graph format are saved and reappear when you reopen the data file.

You create .tpl files. You can create a .tpl file of the defined graph format of any data file and then apply that .tpl file to any data file, including the file from which you created the .tpl file. If you apply a .tpl file created from a data file storing one type of measurement data to a file storing a different type of measurement data, MPMS MultiVu may not copy the full format of the template to the other file, because the other file may be unable to use all format items defined in the template. Section 4.4.4 explains how you create .tpl files. Section 4.4.5 explains how you apply .tpl files.

Chapter 4 Section 4.3 Data Files Types of Data Files


4.3 Types of Data Files Each type of MPMS MultiVu data file performs a unique function by storing a specific type of mea-surement data. A file extension, which MPMS MultiVu adds to the base file name at the time the file is created, identifies the type of data file and protects the function of the file, ensuring that it saves only the type of measurement data it was created to save.

Table 4-3. Name and Function of Data File Types

DATA FILE FILE EXTENSION FUNCTION

Measurement Data .dat Stores pertinent data from measurement.

Scan Data .lastscan Stores raw SQUID voltages from data points read during last scan.

Raw Data .raw Stores raw SQUID voltages from data points read during any number of scans.

Diagnostic Data .diag Stores summary data from any number of scans.

Helium Data1 .dat Records level of helium in dewar.

Environment Log .env Stores specified system parameters.

Field Profile Scan2 .pfl.dat Stores pertinent data from field profile scan.

EDC Data .edc Generated by EDC program.

1 MPMS MultiVu has one helium data file. The base name of the file is heliumgr. 2 The field profile scan data file is available only if the Low Field Profiling option or Ultra Low Field option is installed.

4.3.1 Sample Measurement Data Files For any sample measurement, MPMS MultiVu may save measurement data in up to four different data files, called the sample measurement data files. The measurement data, scan data, raw data, and diagnostic data files are the sample measurement data files. MPMS MultiVu automatically saves sample measurement data to a measurement data file and data from the last scan to a scan data file. MPMS MultiVu creates the raw data and diagnostic data files and then saves data to those files only if you instruct it to do so.

Each sample measurement data file saves data from only one type of measurement. The name of the file indicates which measurement option generated the data stored in the file. The abbreviation of the measurement option$dc, rso, or ac$appears immediately after the base name of the file. For example, the testdata.dc.dat file stores data from a DC sample measurement. The testdata .rso.dat file stores data from an RSO sample measurement. MPMS MultiVu adds file extensions to the base name of the file when it creates the file.

Section 4.3 Chapter 4 Types of Data Files Data Files


4.3.1.1 MEASUREMENT DATA FILES

A measurement data, or .dat, file stores all pertinent data generated by any number of sample measurements taken by one type of measurement option. The first type of measurement option to save data to a .dat file determines the type of measurement option data the file stores.

A .dat file stores measurement data only when it is active, and only one .dat file is active at a time. MPMS MultiVu uses the base name of the active .dat file to create the base names of the other files that are active while the .dat file is active. The Sequence Base Data File Name panel in the control center displays the base name of the .dat file that is active during a sequence run or that will be active when a sequence runs. The Data File panel in the Measure dialog box displays the full name of the .dat file that is active during an immediate measurement or that will be active when an immediate measurement runs.

A .dat file contains one line of data for every identical type of measurement taken while the .dat file is active. If a sequence run includes five DC measurement commands, the active .dat file has five new lines of data. MPMS MultiVu appends data to a .dat file and never overwrites a .dat file.

MPMS MultiVu includes a default .dat file, called data0000. You may create any number of additional .dat files. Section 4.4.1 explains how you create .dat files.

4.3.1.2 SCAN DATA FILES

A scan data, or .lastscan, file stores the raw SQUID voltages from the individual data points read during only the last scan taken as part of a measurement. When the same measurement option runs another measurement, MPMS MultiVu updates the .lastscan file, overwriting the file with the data from the last scan.

One .lastscan file is associated with each .dat file, and the files share the identical base name. MPMS MultiVu creates the .lastscan file the first time a measurement runs while the .dat file is active. MPMS MultiVu overwrites the .lastscan file whenever another measurement runs while the same .dat file is active.

One centering scan data, or center.lastscan, file is associated with each measurement option. MPMS MultiVu creates and names the center.lastscan file the first time the measurement option runs a centering measurement. MPMS MultiVu overwrites the center.lastscan file whenever the same option runs another centering measurement.

A .lastscan file contains one line of data for every data point read during the last scan taken as part of a measurement. The lines summarizing data include the average voltage and the average detrended and demeaned voltage as well as the average regression, detrended, and demeaned fit of all data points in the file. If a .lastscan file includes data from a scan that has 32 data points, the file has 32 lines of data.

The .lastscan file performs the same function as the SQUID response graph that was generated by the MPMSR2 DOS software.

Chapter 4 Section 4.3 Data Files Types of Data Files


4.3.1.3 RAW DATA FILES

The raw data, or .raw, file stores the raw SQUID voltages from the individual data points read during any number of scans taken by one type of measurement option. MPMS MultiVu creates a .raw file only if you instruct it to do so. Each .raw file you create is associated with one .dat file, and the files share the identical base name. MPMS MultiVu saves data to the .raw file only while the file’s associated .dat file is active.

A .raw file contains one line of data for every data point read during every scan run while the file is active. The lines summarizing data from the last scan that was run include the average voltage and fit of all data points in the .raw file. If a .raw file includes data from two scans and each scan has 10 data points, the file has 20 lines of data, and lines 11 through 20 include the average voltage and the average detrended and demeaned voltage as well as the average regression, detrended, and demeaned fit of all data points in the file. MPMS MultiVu always appends data to a .raw file and never overwrites a .raw file.

4.3.1.4 DIAGNOSTIC DATA FILES

The diagnostic data, or .diag, file stores summary data from any number of scans taken by one type of measurement option. MPMS MultiVu creates a .diag file only if you instruct it to do so. Each .diag file you create is associated with one .dat file, and the files share the identical base name. MPMS MultiVu saves data to the .diag file only while the file’s associated .dat file is active.

The .diag file contains one line of data for every scan performed while the file is active. If a .diag file includes data from 10 scans, the file has 10 lines of data. MPMS MultiVu always appends data to a .diag file and never overwrites a .diag file.

4.3.2 Helium Data File The helium data, or heliumgr.dat, file stores the helium-level data from the last helium fill. The file plots the level of helium in the dewar against the length of time of the helium-filling operation. The Utilities!Helium Fill option opens the graph view of the heliumgr.dat file. MPMS MultiVu has one heliumgr.dat file that it overwrites whenever you run another helium fill.

The heliumgr.dat file has one line of data for every helium level recorded during the last helium fill. Each line has two data entries: the timestamp and the helium level. The MPMS system defines the time interval at which the heliumgr.dat file stores data.

4.3.3 Environment Log Files The environment log, or .env, file stores time-based system data parameters. Once a .env file begins to store data, it stores data until it is instructed to stop.

You create all .env files (see section 4.4.2). You specify which system data parameters MPMS MultiVu saves to the .env file, and you specify the time interval at which MPMS MultiVu saves the data. Only one .env file stores data at a time.

Section 4.3 Chapter 4 Types of Data Files Data Files


The .env file has one line of data for each data reading. The number of data readings is determined by the specified time interval. The content of each line of data is determined by the specified data parameters. By default, MPMS MultiVu appends data to a .env file. You can instruct MPMS MultiVu to overwrite a .env file.

The .env file is also referred to as the log MPMS file.

4.3.4 Field Profile Scan Files The field profile scan, or .pfl, file stores all pertinent data from a field profile scan. MPMS MultiVu creates a .pfl file during a field profile scan. The .pfl files are available only if the Low Field Profiling option or the Ultra Low Field option is installed.

The .pfl file contains one line of data for every field recorded during the field profile scan. By default, MPMS MultiVu appends data to a .pfl file. You can instruct MPMS MultiVu to overwrite the file.

4.3.5 EDC Data Files Data files created in an EDC program by using the EDC data file commands use the same format and naming conventions as all other MPMS MultiVu measurement data files, but add the .edc extension to the data file name. The Magnetic Property Measurement System: External Device Control Language User’s Manual discusses the EDC data files in detail.

Chapter 4 Section 4.4 Data Files Data File Management


4.4 Data File Management

4.4.1 Creating a Measurement Data File If you specify the base name of a new .dat file before you run a measurement, you can save data from that measurement to the new file.

The following procedures explain how you create a .dat file to store DC measurement data. The procedures you use to create a .dat file to store RSO measurement data or AC measurement data are nearly identical.

4.4.1.1 CREATING A MEASUREMENT DATA FILE TO SAVE IMMEDIATE MEASUREMENT DATA

1. Select Measure!DC. The Measure DC dialog box opens (see figure 3-9). 2. Select Change. The Select or Enter a New DC Data File dialog box opens. By default, the

dialog box lists all .dat files. 3. Select the directory in which the data files will reside, if necessary. The default directory is

C:\QdMpms\Data. If you select a directory, all new data files will reside in that directory. 4. Enter only the base name of the new .dat file, and then select Open. The Select or Enter a

New DC Data File dialog box closes, and the Measure DC dialog box appears again. The full name of the .dat file, including the file extensions, appears in the Data File panel in the Measure DC dialog box.

5. Select the Include Diagnostics Data and Include Raw Data check boxes if you want MPMS MultiVu to create the .diag and .raw files.

6. Do the following if you want to modify the default graph format of any data file that will store the immediate measurement data: (a) select View, (b) select the file, (c) select Open, and then (d) modify the graph format as necessary. Refer to section 4.6.

Selecting View prompts MPMS MultiVu to create the .dat and .lastscan files and$if the Include Diagnostics Data and Include Raw Data check boxes are selected$the .diag and .raw files. The new files contain only header information, which defines the default graph format.

7. Select Measure to run the measurement. If you did not select View, MPMS MultiVu creates the data files when it completes the first measurement. If you run multiple measurements while the same data files are active, MPMS MultiVu appends data to the files.

Section 4.4 Chapter 4 Data File Management Data Files


4.4.1.2 CREATING A MEASUREMENT DATA FILE TO SAVE SEQUENCE MEASUREMENT DATA

1. Select the Sequence Base Data File Name Change button in the control center. The Select a Data File dialog box opens. By default, the dialog box lists all .dat files.

2. Select the directory in which the data files will reside, if necessary. If you select a directory, all new data files will reside in that directory.

3. Enter only the base name of the new .dat file, and then select Open. The Select a Data File dialog box closes. The base name of the .dat file appears in the Sequence Base Data File Name panel in the control center. MPMS MultiVu has deleted any file extensions you added to the base file name.

4. Open the selected sequence file if you want to modify the DC measurement commands. In the command dialog box, select the Include Diagnostic Data and Include Raw Data check boxes if you want MPMS MultiVu to create the .diag and .raw files. Section 5.3.2 explains how you edit a sequence.

5. Save the selected sequence file if you have edited it. 6. Select the Run button in the control center in order to run the sequence.

MPMS MultiVu creates the .dat and .lastscan files when it completes the first measure-ment in the sequence. MPMS MultiVu also creates the .diag and .raw files if you instructed it to do so. MPMS MultiVu creates the files and adds the file extensions to the base file names when it knows which type of measurement data the files will store. Once a measurement is complete, you may open any of the active data files. Do the following: (a) select the Sequence Base Data File Name View button in the control center, (b) select a data file in the Select a Data File dialog box, and then (c) select Open. If you run multiple sequences while the same data files are active, MPMS MultiVu appends data to those files.

4.4.1.3 CREATING A MEASUREMENT DATA FILE WITHIN A SEQUENCE

1. Select the Selected Sequence Edit button in the control center. A sequence editor opens and lists all commands in the selected sequence. The sequence command bar also opens unless it is hidden or already open.

2. Double-click on the Set Datafile command, which is in the Measure command group in the sequence command bar. Set Datafile opens a dialog box that lists all .dat files.

3. Select the directory in which the data files will reside, if necessary. If you select a directory, all new data files will reside in that directory.

4. Enter only the base name of the new .dat file, and then select Open. The Select a Data File dialog box closes. The base name and file location of the .dat file appear on a single command line in the sequence editor. MPMS MultiVu has deleted any file extensions you added to the base file name.

5. Edit the sequence file in order to correctly position Set Datafile, if necessary. Set Datafile must precede a measurement command if you want to save the data generated by that command to the new files. Section 5.3.2 explains how you edit a sequence.

6. Modify the DC measurement commands, if necessary. In the command dialog box, select the Include Diagnostic Data and Include Raw Data check boxes if you want MPMS MultiVu to create the .diag and .raw files.

7. Save the sequence.



8. Select the Run button in the control center in order to run the sequence. MPMS MultiVu creates the .dat and .lastscan files when it completes the first measure-ment after it reads Set Datafile. MPMS MultiVu also creates the .diag and .raw files if you instructed it to do so. The files created with Set Datafile remain active throughout the sequence run unless MPMS MultiVu reads another Set Datafile command. During the sequence run, the base name of the data files created with Set Datafile appears in the Sequence Status panel and the sequence status panels, but does not appear in the Sequence Base Data File Name panel.

4.4.2 Creating an Environment Log File 1. Select Utilities!Log MPMS Data. The Log Data dialog box opens. 2. Select the General tab. You use the General tab to select an environment log file and to specify

how frequently MPMS MultiVu logs data to the file.

Figure 4-1. General Tab in Log Data Dialog Box

3. Select Browse. The Select an Environment Data File dialog opens and lists all .env files. 4. Select the directory in which the .env file will reside, if necessary. If you select a directory,

all new data files will reside in that directory. 5. Enter only the base name of the new .env file, then select Open. The full name of the .env

file appears at the top of the Data File pull-down menu in the General tab. MPMS MultiVu has added the file extension to the base file name because it knows which type of data the file will store. Notice that you select the Overwrite check box if you want to overwrite an existing .env file. By default, MPMS MultiVu appends data to .env files.

6. Enter the time interval, in seconds, defining how frequently MPMS MultiVu logs data to the .env file. The time interval may be any length from 0.25 seconds to 99,999 seconds.

Section 4.4 Chapter 4 Data File Management Data Files


7. Select the Standard Items tab. You use the Standard Items tab to select the system data parameters that MPMS MultiVu logs to the .env file.

Figure 4-2. Standard Items Tab in Log Data Dialog Box

8. Select system parameters. Click on Select All to save all parameters. Click on Unselect All to deselect all parameters. When you select a parameter, its value appears in the Standard Items tab. If you select a large number of parameters, data logging occurs more slowly.

9. Select Start to begin logging the specified parameters. MPMS MultiVu creates the .env file when it begins logging data. At any time, you can specify different parameters for MPMS MultiVu to log. However, while MPMS MultiVu logs the data, you cannot redefine the time interval at which the data is logged. You cannot run multiple .env files.

10. Select View Data in the General tab in order to open the .env file. 11. Select Stop to stop logging data. MPMS MultiVu logs data until you instruct it to stop.

4.4.3 Changing the Sequence Base Data File Name 1. Select the Sequence Base Data File Name Change button in the control center. The Select a

Data File dialog box opens. By default, the dialog box lists all .dat files. 2. Select a .dat file, then select Open. The base name of the .dat file appears in the Sequence

Base Data File Name panel in the control center. The file does not open.



4.4.4 Creating a Graph Template File 1. Select an open data file, and verify that the graph view is active. 2. Modify the graph format, if necessary. Refer to section 4.6. 3. Select Graph!Save Template As. The Save as a Graph Template File dialog box opens

and lists all .tpl files. The full name of the data file you are using to create the template is displayed. However, MPMS MultiVu has replaced the original file extension with the .tpl extension.

4. Select Open or specify a different file name and then select Open. MPMS MultiVu creates the .tpl file.

4.4.5 Applying a Graph Template File 1. Select an open data file, and verify that the graph view is active. 2. Select Graph!Apply Template. The Apply a Template to the Current Graph dialog box

opens and lists all .tpl files. 3. Select a .tpl file, then select Open. MPMS MultiVu applies the .tpl file to the graph format

of the data file, modifying the graph format so that it is defined by the template. If you apply a .tpl file created from a data file storing one type of measurement data to a file storing a different type of measurement data, MPMS MultiVu does not necessarily copy the full format of the template to the data file; the data file may not be able to use all format items defined in the .tpl file.

4.4.6 Printing a Graph Before you print any graph view or sequence file, you can use the File!Print Preview option to see what the graph or sequence file will look like when it is printed. The view window also includes a Print button.

1. Select an open data file, and verify that the graph view is active. 2. Select File!Print. The Print Parameters dialog box opens. The dialog box defines the

appearance of the printed graph. 3. Specify what labels, such as the name and path of the data file, you want to print on the graph.

Also specify the printing options. 4. Select OK. The Print dialog box opens. 5. Select a printer and define the printer properties, specify the number of copies, and so on. 6. Select OK. The graph is printed.

Section 4.5 Chapter 4 Data-Viewing Formats Data Files


4.5 Data-Viewing Formats MPMS MultiVu includes four data-viewing formats$the graph view, record view, table view, and raw data view$that give you four different ways of examining the information stored in a data file. The graph view is the default viewing format. Every data file opens in the graph view. Once a data file is open, you can select any of the other three viewing formats. Multiple views of a data file or of several files may be open at one time.

Commands in the View menu and Graph pop-up menu open and select viewing formats. You open the Graph pop-up menu by right-clicking the mouse inside any graph window.

4.5.1 Graph View The graph view is a plot of data points that MPMS MultiVu has saved to a data file. The graph plots only the specified data points and may not plot all data points saved to the file. MPMS MultiVu uses the current graph configuration, or .gph, file to plot the points.

One Plot in Graph View Two Plots in Graph View

Figure 4-3. Graph View

In the graph view, one data point is highlighted, or selected. If you double-click close to the selected data point, the record view opens and lists the values of all parameters for that data point. If you double-click a part of the graph area that is not near the selected data point, the table view opens and lists all parameters for all data points in the data file. To select a different data point, click on that data point.

The graph view automatically opens when you open a data file. If a data file is open and selected, but the graph view is not selected, you can open the graph view by selecting the View!Graph option.

Chapter 4 Section 4.5 Data Files Data-Viewing Formats


4.5.2 Record View The record view is a table listing the value of all parameters for one data point that MPMS MultiVu has saved to a data file. Each row in the table displays the name and value of one parameter. The number in the left-hand column of every row helps separate the rows and identifies which column in the table-view table displays the same parameter data. The number of rows in the record-view table is determined by the number of parameters associated with the data point.

Figure 4-4. Record View

The header in the record window indicates which data point you are examining. The data point is always the last data point selected in the graph view or table view. To select a different data point, use the First, Prev, Next, and Last buttons that are at the bottom of the record window, or click on a data point in the graph view or on a row in the table view.

You can open the record view whenever a data file is open and selected, but the record view is not selected. To open the record view, you can select the View!Record option. You can also open the record view by double-clicking on any point in the graph view or by double-clicking on any row in the table view.

Section 4.5 Chapter 4 Data-Viewing Formats Data Files


4.5.3 Table View The table view is a table listing the value of all parameters for all data points that MPMS MultiVu has saved to a data file. Each row in the table displays all parameter data for one data point. The number in the left-hand column of a row identifies the order in which the data point was read in the sequence of data points comprising the data file. The number of data points read determines the number of rows in the table.

Figure 4-5. Table View

The highlighted, or selected, row in the table view identifies the last data point selected in the graph view or record view. If you double-click on the selected row, the record listing the value of all param-eters for that data point opens. To select a different data point, click on another row in the table view.

You can open the table view whenever a data file is open and selected, but the table view is not selected. To open the table view, you can select the View!Table option.

4.5.4 Raw Data View The raw data view is a text editor view of a data file. You can open the raw data view whenever a data file is open and selected, but the raw data view is not selected. To open the raw data view, you can select the View!Raw Data option.

Chapter 4 Section 4.6 Data Files Graph Formats


4.6 Graph Formats The graph format is the physical appearance and layout of the graph view of a data file. A graph’s appearance refers to the gridlines and data indicators the graph uses to plot different types of data stored in the file. The header section of a data file defines the default graph format of the file. You cannot change the default graph format. However, when the graph view is active, you can modify its appearance in multiple ways.

Commands in the Graph menu and Graph pop-up menu change the graph format. Graph menu and Graph pop-up menu options are nearly identical. However, Graph menu options emphasize opening and saving files; Graph pop-up menu options emphasize viewing data. The Graph pop-up menu is available only when the graph view is active. You open the Graph pop-up menu by right-clicking the mouse inside any graph window.

4.6.1 Selecting Gridlines and Data Indicators 1. Select an open data file, and verify that the graph view is active. 2. Select Graph!Appearance. The Appearance submenu opens. The submenu can contain up to

four numbered Plot options. One option is enabled for each plot in the graph view. 3. Select a Plot option. A pop-up dialog box opens and

identifies which gridline and data indicator options define the format of the selected plot.

4. Select options in the Plot Appearance pop-up dialog box. If the active graph view has multiple plots, you can select Apply to All Plots to apply the format of the selected plot to all plots in the graph view.

5. Select Apply to apply the changes and keep the pop-up dialog box open or select OK to apply the changes and close the dialog box.

The Graph!Auto Scale All Plots option or the Graph pop-up menu!Auto Scale All Plots option adjusts the axis limits so that the plotted data points are comfortably spaced and you can see all of your data.

The Graph pop-up menu!X Axis Auto Scale toggle option or Y Axis Auto Scale toggle option adjusts the x-axis gridlines or y-axis gridlines, respectively, so that the plotted data points are comfortably spaced.

Figure 4-6. Plot Appearance

Dialog Box

Section 4.6 Chapter 4 Graph Formats Data Files


4.6.2 Plotting Parameters 1. Select an open data file, and verify that the graph view is active. 2. Select Graph!Data Selection. The Data Selection dialog box opens and lists all available axes

and parameters that may appear in the graph.

Figure 4-7. Data Selection Dialog Box

3. Use the Axis pull-down menus to select the axes on which MPMS MultiVu plots data in the graph. Each graph must have one x-axis and one y-axis. A graph may have up to four y-axes. To remove an extra y-axis, select off in the corresponding pull-down menu.

4. Select the Log check box associated with each axis if you want to logarithmically scale the parameter data on that axis. If Log is not selected, MPMS MultiVu scales the data linearly.

5. Use the Data pull-down menu associated with each axis to select the type of parameter data plotted on the axis. If the graph includes multiple y-axes, you can select a different type of parameter data for each y-axis. When multiple y-axes plot different types of data, MPMS MultiVu creates a separate plot of each x-axis"and"y-axis combination within the graph window. An asterisk appearing to the left of any parameter name in a Data pull-down menu indicates that MPMS MultiVu has not found data for that parameter. The Data pull-down menus list only the types of parameter data that are in the specified data group. You use the Data Group pull-down menu to specify the data group. Refer to step 7.

6. Select the Auto check box associated with each axis in order to automatically scale the axis. If Auto is not selected, you can specify the minimum and maximum values for the axis. Enter the minimum and maximum values in the Min and Max text boxes, respectively. The default values appearing in the Min and Max text boxes represent the axis limits presently defined by the autoscale function.

7. Use the Data Group pull-down menu to specify the data group. The data group is a subgroup of similar data parameter types. Select Longitudinal to plot only parameters used by the longitudinal SQUID. Select Transverse to plot only parameters used by the transverse SQUID. Select All to plot all available parameters. MPMS MultiVu can plot only the data parameters in the specified data group.

8. Select the time interval the x-axis uses to represent time.

Chapter 4 Section 4.6 Data Files Graph Formats


9. Select the method of displaying time in the graph. Select Relative to start the time scale at zero. Select Absolute to use the absolute timestamp value that is stored in the data file.

10. Select the graph’s display range. Select All Records to plot all data points. Select Last or From to display only specified data points.

11. Select Apply to apply the changes and keep the Data Selection dialog box open or select OK to apply the changes and close the dialog box.

4.6.3 Magnifying a Graph 1. Select an open data file, and verify that the graph view is active. 2. Click anywhere on the graph, drag the mouse through the graph so that you select the part of the

graph you want to magnify, and then release the mouse. The selected part of the graph is magnified. You may repeat this procedure any number of times.

3. Select Graph!Zoom Previous to return a magnified graph to its previous magnification. You can select Zoom Previous any number of times until the graph returns to its original size.

4.6.4 Restoring the Current Graph Configuration File Select Graph!Restore Graph to return the graph format of a data file to the format defined by the current graph configuration, or .gph, file. The current .gph file is the file created the last time the data file was closed. You may select Restore Graph at any time.

4.6.5 Restoring the Default Graph Format Select Graph!Default Graph to return the graph format of a data file to the default graph format defined in the data file header. You may select Default Graph at any time.

Documents

MPMS MultiVu Application UserÕs Manual - Our Story · PDF fileQuantum Design MPMS MultiVu Application UserÕs Manual i CONTENTS Table of Contents PREFACE Contents and Conventions